fix(appset): allow for shorthand git refs in git generators #15427

[rumstead]

fixes #15427

The GitHub webhook sends the full branch ref eg, refs/heads/env/dev. There is code to parse out the revision which will correctly parse out env/dev. However, in the appset, if someone uses the shorthand ref, env/dev it will get parsed out incorrectly to dev.

Checklist:

• Either (a) I've created an enhancement proposal and discussed it with the community, (b) this is a bug fix, or (c) this does not need to be in the release notes.
• The title of the PR states what changed and the related issues number (used for the release note).
• The title of the PR conforms to the Toolchain Guide
• I've included "Closes [ISSUE #]" or "Fixes [ISSUE #]" in the description to automatically close the associated issue.
• I've updated both the CLI and UI to expose my feature, or I plan to submit a second PR with them.
• Does this PR require documentation updates?
• I've updated documentation as required by this PR.
• I have signed off all my commits as required by DCO
• I have written unit and/or e2e tests for my change. PRs without these are unlikely to be merged.
• My build is green (troubleshooting builds).
• My new feature complies with the feature status guidelines.
• I have added a brief description of why this PR is necessary and/or what this PR solves.
• Optional. My organization is added to USERS.md.
• Optional. For bug fixes, I've indicated what older releases this fix should be cherry-picked into (this may or may not happen depending on risk/complexity).

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[codecov]

Codecov Report

Attention: Patch coverage is 95.83333% with 1 line in your changes missing coverage. Please review.

Project coverage is 55.78%. Comparing base (63b6565) to head (b11fc27).
Report is 3 commits behind head on master.

Files with missing lines	Patch %	Lines
...t-controller/commands/applicationset_controller.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #19783      +/-   ##
==========================================
+ Coverage   55.77%   55.78%   +0.01%     
==========================================
  Files         320      320              
  Lines       44206    44203       -3     
==========================================
+ Hits        24656    24659       +3     
- Misses      16988    16993       +5     
+ Partials     2562     2551      -11     

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[ishitasequeira]

Overall change looks good!!

[wanghong230]

Thank you for the proper test!