base task: attempt to log CheckpointLogger errors for on_timeout and on_failure

[matt-codecov]

the UploadFlow reliability metrics rely on there being a checkpoint logged for every way the flow can end, whether it's a success or a failure. looking at the data, it appears 40-60% of flow endings aren't captured. this means we can't totally trust our calculated reliability rate

i am not totally clear on how celery calls on_failure() and on_timeout(), but this PR attempts to load any checkpoints data it can find in them and log an error event. ideally this will increase our share of captured endings and make the metrics more accurate

on_timeout() is a member on a celery Request which we've subclassed as BaseCodecovRequest. it doesn't receive kwargs as an argument, but according to docs it has a kwargs property which presumably holds the kwargs that the task was scheduled with. on_failure() is a member on the task and one of its arguments is kwargs. a non-retried UploadTask will not have any checkpoints data in its kwargs, but i think a retried UploadTask and future tasks should at least have a beginning checkpoint.

doing this creates a possibility that some endings will be double-counted:

• a SoftTimeLimitException may result in both on_timeout() and on_failure() being called
• a SoftTimeLimitException allows the task to clean up gracefully. if it takes too long, a hard TimeLimitException is raised? and it's possible if this happens that on_timeout() will be called twice
• generally if we catch an error inside the celery task we still tell celery the task finished successfully and go to on_success(), but i don't know for sure that there are not cases where we log an error and then also wind up in on_failure() or on_retry()

[codecov]

Codecov Report

Attention: Patch coverage is 82.60870% with 4 lines in your changes missing coverage. Please review.

Project coverage is 98.00%. Comparing base (48ce427) to head (1cd2e55).
Report is 35 commits behind head on main.

✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
tasks/base.py	77.77%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #794      +/-   ##
==========================================
- Coverage   98.01%   98.00%   -0.01%     
==========================================
  Files         443      443              
  Lines       36615    36637      +22     
==========================================
+ Hits        35887    35905      +18     
- Misses        728      732       +4     

Flag	Coverage Δ
integration	98.00% <82.60%> (-0.01%)	⬇️
unit	98.00% <82.60%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
NonTestCode	95.85% <82.60%> (-0.03%)	⬇️
OutsideTasks	97.99% <100.00%> (+<0.01%)	⬆️

Files with missing lines	Coverage Δ
helpers/checkpoint_logger/flows.py	100.00% <100.00%> (ø)
tasks/base.py	95.04% <77.77%> (-1.69%)	⬇️

[codecov-notifications]

Codecov Report

Attention: Patch coverage is 82.60870% with 4 lines in your changes missing coverage. Please review.

✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
tasks/base.py	77.77%	4 Missing ⚠️

@@            Coverage Diff             @@
##             main     #794      +/-   ##
==========================================
- Coverage   98.01%   98.00%   -0.01%     
==========================================
  Files         443      443              
  Lines       36615    36637      +22     
==========================================
+ Hits        35887    35905      +18     
- Misses        728      732       +4     

Flag	Coverage Δ
integration	98.00% <82.60%> (-0.01%)	⬇️
unit	98.00% <82.60%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
NonTestCode	95.85% <82.60%> (-0.03%)	⬇️
OutsideTasks	97.99% <100.00%> (+<0.01%)	⬆️

Files with missing lines	Coverage Δ
helpers/checkpoint_logger/flows.py	100.00% <100.00%> (ø)
tasks/base.py	95.04% <77.77%> (-1.69%)	⬇️

[codecov-qa]

Codecov Report

Attention: Patch coverage is 82.60870% with 4 lines in your changes missing coverage. Please review.

Project coverage is 98.00%. Comparing base (48ce427) to head (1cd2e55).
Report is 35 commits behind head on main.

✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
tasks/base.py	77.77%	4 Missing ⚠️

@@            Coverage Diff             @@
##             main     #794      +/-   ##
==========================================
- Coverage   98.01%   98.00%   -0.01%     
==========================================
  Files         443      443              
  Lines       36615    36637      +22     
==========================================
+ Hits        35887    35905      +18     
- Misses        728      732       +4     

Flag	Coverage Δ
integration	98.00% <82.60%> (-0.01%)	⬇️
unit	98.00% <82.60%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
NonTestCode	95.85% <82.60%> (-0.03%)	⬇️
OutsideTasks	97.99% <100.00%> (+<0.01%)	⬆️

Files with missing lines	Coverage Δ
helpers/checkpoint_logger/flows.py	100.00% <100.00%> (ø)
tasks/base.py	95.04% <77.77%> (-1.69%)	⬇️

[codecov-public-qa]

Codecov Report

Attention: Patch coverage is 82.60870% with 4 lines in your changes missing coverage. Please review.

Project coverage is 98.00%. Comparing base (48ce427) to head (1cd2e55).

✅ All tests successful. No failed tests found.

@@            Coverage Diff             @@
##             main     #794      +/-   ##
==========================================
- Coverage   98.01%   98.00%   -0.01%     
==========================================
  Files         443      443              
  Lines       36615    36637      +22     
==========================================
+ Hits        35887    35905      +18     
- Misses        728      732       +4     

Flag	Coverage Δ
integration	98.00% <82.60%> (-0.01%)	⬇️
unit	98.00% <82.60%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
NonTestCode	95.85% <82.60%> (-0.03%)	⬇️
OutsideTasks	97.99% <100.00%> (+<0.01%)	⬆️

Files	Coverage Δ
helpers/checkpoint_logger/flows.py	100.00% <100.00%> (ø)
tasks/base.py	95.04% <77.77%> (-1.69%)	⬇️

[matt-codecov]

#823