remove unused code

[nora-codecov]

Purpose/Motivation

Found some old code that's no longer in use while I was looking into webhooks and how we set them up.
I checked with application team and it seems like they aren't using the _reset_webhook endpoint.
All of the functionality to set up webhooks now lives on worker. And it looks like we don't have a delete_webhook anymore.

[codecov-qa]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.58%. Comparing base (769ed11) to head (f8ddeac).

✅ All tests successful. No failed tests found.

@@           Coverage Diff           @@
##             main     #676   +/-   ##
=======================================
  Coverage   91.57%   91.58%           
=======================================
  Files         628      627    -1     
  Lines       16671    16641   -30     
=======================================
- Hits        15266    15240   -26     
+ Misses       1405     1401    -4     

Flag	Coverage Δ
unit	91.58% <100.00%> (+<0.01%)	⬆️
unit-latest-uploader	91.58% <100.00%> (+<0.01%)	⬆️

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

Files	Coverage Δ
api/internal/repo/views.py	100.00% <100.00%> (ø)

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[codecov-notifications]

Codecov Report

All modified and coverable lines are covered by tests ✅

✅ All tests successful. No failed tests found.

📢 Thoughts on this report? Let us know!

[codecov-public-qa]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.58%. Comparing base (769ed11) to head (f8ddeac).

✅ All tests successful. No failed tests found.

@@           Coverage Diff           @@
##             main     #676   +/-   ##
=======================================
  Coverage   91.57%   91.58%           
=======================================
  Files         628      627    -1     
  Lines       16671    16641   -30     
=======================================
- Hits        15266    15240   -26     
+ Misses       1405     1401    -4     

Flag	Coverage Δ
unit	91.58% <100.00%> (+<0.01%)	⬆️
unit-latest-uploader	91.58% <100.00%> (+<0.01%)	⬆️

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

Files	Coverage Δ
api/internal/repo/views.py	100.00% <100.00%> (ø)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.93%. Comparing base (769ed11) to head (f8ddeac).

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@               Coverage Diff                @@
##               main       #676        +/-   ##
================================================
- Coverage   95.94000   95.93000   -0.01000     
================================================
  Files           806        806                
  Lines         17988      17973        -15     
================================================
- Hits          17258      17243        -15     
  Misses          730        730                

Flag	Coverage Δ
unit	91.58% <100.00%> (+<0.01%)	⬆️
unit-latest-uploader	91.58% <100.00%> (+<0.01%)	⬆️

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

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