fix(appset): Always remove ownerReferences when appset policy doesn't allow app's deletion (#12172)

[mikutas]

This is following up of #15903 , and relates to #12172 .
The background is here.

As-is (master)

When deleting ApplicationSet, there are two ways to process dependent Applications.

• ApplicationSet has resources-finalizer.argocd.argoproj.io finalizer: ownerReferences of dependent Apps will be deleted (and Apps will be orphaned)
• ApplicationSet doesn't have the finalizer: ownerReferences won't be deleted (and Apps will be deleted)

To-be (this PR)

The finalizer doesn't matter.
When policy doesn't allow deletion, ownerReferences will be always deleted (and Apps will be always orphaned).

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.
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[codecov]

Codecov Report

Attention: 8 lines in your changes are missing coverage. Please review.

Comparison is base (35f1ee7) 49.49% compared to head (82b13e3) 49.49%.

Files	Patch %	Lines
...cationset/controllers/applicationset_controller.go	0.00%	8 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #16506   +/-   ##
=======================================
  Coverage   49.49%   49.49%           
=======================================
  Files         270      270           
  Lines       47489    47488    -1     
=======================================
  Hits        23506    23506           
+ Misses      21672    21671    -1     
  Partials     2311     2311           

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[gdsoumya]

LGTM