fix: properly handle shutdown signal for admin dashboard (#22758)

[ramilmsh]

Fixes: #22758

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.
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[ramilmsh]

I'm pretty sure this is not how this bug is supposed to be fixed, and I've most likely not filled out the PR correctly. Feel free to close, if that's the case. If I'm on the right track, however - I'd be happy to clean it up and get it ready for merge

[codecov]

Codecov Report

❌ Patch coverage is 0% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 59.98%. Comparing base (25dc960) to head (7ecf09e).
⚠️ Report is 564 commits behind head on master.

Files with missing lines	Patch %	Lines
cmd/argocd/commands/admin/dashboard.go	0.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #23050      +/-   ##
==========================================
- Coverage   59.98%   59.98%   -0.01%     
==========================================
  Files         343      343              
  Lines       57850    57853       +3     
==========================================
  Hits        34701    34701              
+ Misses      20373    20371       -2     
- Partials     2776     2781       +5     

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[blakepettersson]

See #23231

[blakepettersson]

Fixed with #23231. Thank you for the work!