feat(appcontroller): Using impersonation when an application is deleted

[anandf]

When implementing the app sync with impersonation feature, application controller impersonates only for a sync operation. This PR is enhancing that feature for the application deletion as well. When admin users want to avoid accidental deletion of resources, they can control it by removing the delete access to the impersonated service account.

Related PR: #17403
Feature proposal for impersonation: #14255

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 75.00000% with 4 lines in your changes missing coverage. Please review.

Project coverage is 55.63%. Comparing base (6daaac5) to head (82058d5).

Files with missing lines	Patch %	Lines
controller/appcontroller.go	75.00%	3 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #21800      +/-   ##
==========================================
- Coverage   55.64%   55.63%   -0.02%     
==========================================
  Files         339      339              
  Lines       56876    56892      +16     
==========================================
+ Hits        31651    31653       +2     
- Misses      22583    22593      +10     
- Partials     2642     2646       +4     

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