Fix panic in PAC controller on delete tag event in GitLab

[zakisk]

fixed panic in PAC controller when a tag is deleted on gitlab.

https://issues.redhat.com/browse/SRVKP-6636

https://redhat-internal.slack.com/archives/C04PZ7H0VA8/p1727708590297089

Changes

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[codecov]

Codecov Report

Attention: Patch coverage is 62.50000% with 3 lines in your changes missing coverage. Please review.

Project coverage is 65.17%. Comparing base (a10162c) to head (77624f4).
Report is 9 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/provider/gitlab/parse_payload.go	62.50%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1783      +/-   ##
==========================================
+ Coverage   65.16%   65.17%   +0.01%     
==========================================
  Files         174      174              
  Lines       13250    13258       +8     
==========================================
+ Hits         8634     8641       +7     
  Misses       4043     4043              
- Partials      573      574       +1     

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[chmouel]

seems like your test is failing on --- FAIL: TestGitlabDeleteTagEvent (16.82s)
have you tested it ?

    gitlab_delete_tag_event_test.go:49: assertion failed: error is not nil: could not find a match using the labelSelector: app.kubernetes.io/name=controller in container pac-controller for regexp: event Delete Tag Push Hook is not supported*

[zakisk]

@chmouel yes, tested on my local machine and it was working fine.