Perform parallel report merging within the Report lock

[Swatinem]

This was an oversight in the original parallel processing PR.

The final merge step is now performed while holding the "master Report" lock to guard against concurrent mutation.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.03%. Comparing base (98629d2) to head (3515688).
Report is 3 commits behind head on main.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #762   +/-   ##
=======================================
  Coverage   98.02%   98.03%           
=======================================
  Files         438      438           
  Lines       36389    36397    +8     
=======================================
+ Hits        35672    35680    +8     
  Misses        717      717           

Flag	Coverage Δ
integration	98.03% <100.00%> (+<0.01%)	⬆️
unit	98.03% <100.00%> (+<0.01%)	⬆️

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

Components	Coverage Δ
NonTestCode	95.89% <100.00%> (+<0.01%)	⬆️
OutsideTasks	98.03% <ø> (ø)

Files with missing lines	Coverage Δ
tasks/upload_finisher.py	96.12% <100.00%> (+0.12%)	⬆️

[codecov-notifications]

Codecov Report

All modified and coverable lines are covered by tests ✅

✅ All tests successful. No failed tests found.

@@           Coverage Diff           @@
##             main     #762   +/-   ##
=======================================
  Coverage   98.02%   98.03%           
=======================================
  Files         438      438           
  Lines       36389    36397    +8     
=======================================
+ Hits        35672    35680    +8     
  Misses        717      717           

Flag	Coverage Δ
integration	98.03% <100.00%> (+<0.01%)	⬆️
unit	98.03% <100.00%> (+<0.01%)	⬆️

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

Components	Coverage Δ
NonTestCode	95.89% <100.00%> (+<0.01%)	⬆️
OutsideTasks	98.03% <ø> (ø)

Files with missing lines	Coverage Δ
tasks/upload_finisher.py	96.12% <100.00%> (+0.12%)	⬆️

[codecov-qa]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.03%. Comparing base (98629d2) to head (3515688).
Report is 3 commits behind head on main.

✅ All tests successful. No failed tests found.

@@           Coverage Diff           @@
##             main     #762   +/-   ##
=======================================
  Coverage   98.02%   98.03%           
=======================================
  Files         438      438           
  Lines       36389    36397    +8     
=======================================
+ Hits        35672    35680    +8     
  Misses        717      717           

Flag	Coverage Δ
integration	98.03% <100.00%> (+<0.01%)	⬆️
unit	98.03% <100.00%> (+<0.01%)	⬆️

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

Components	Coverage Δ
NonTestCode	95.89% <100.00%> (+<0.01%)	⬆️
OutsideTasks	98.03% <ø> (ø)

Files with missing lines	Coverage Δ
tasks/upload_finisher.py	96.12% <100.00%> (+0.12%)	⬆️

[codecov-public-qa]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.03%. Comparing base (98629d2) to head (3515688).

✅ All tests successful. No failed tests found.

@@           Coverage Diff           @@
##             main     #762   +/-   ##
=======================================
  Coverage   98.02%   98.03%           
=======================================
  Files         438      438           
  Lines       36389    36397    +8     
=======================================
+ Hits        35672    35680    +8     
  Misses        717      717           

Flag	Coverage Δ
integration	98.03% <100.00%> (+<0.01%)	⬆️
unit	98.03% <100.00%> (+<0.01%)	⬆️

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

Components	Coverage Δ
NonTestCode	95.89% <100.00%> (+<0.01%)	⬆️
OutsideTasks	98.03% <ø> (ø)

Files	Coverage Δ
tasks/upload_finisher.py	96.12% <100.00%> (+0.12%)	⬆️