docs: unset finalizer before deleting an app non-cascadingly

[beyondbill]

Signed-off-by: Bo Huang beyondbill@users.noreply.github.com

Our organization sets the finalizer from the default ArgoCD application template. Therefore it is risky to assume that ArgoCD applications always start without the finalizer unless set by argocd app delete with --cascade, as the current docs indicate. It actually caused a P1 incident when one of our SREs followed the instruction in the docs to delete all ArgoCD applications "non-cascadingly" by running kubectl delete app, only to find all staging and prod services deleted! It's preferable to always unset the finalizer before a non-cascade deletion unless the operator knows with certainty that the finalizer has never been set before.

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• (c) this does not need to be in the release notes.
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[codecov]

Codecov Report

Base: 47.71% // Head: 47.71% // No change to project coverage 👍

Coverage data is based on head (acd37f6) compared to base (338245e).
Patch has no changes to coverable lines.

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #10949   +/-   ##
=======================================
  Coverage   47.71%   47.71%           
=======================================
  Files         246      246           
  Lines       41908    41908           
=======================================
  Hits        19996    19996           
  Misses      19914    19914           
  Partials     1998     1998           

Impacted Files	Coverage Δ
util/settings/settings.go	49.36% <0.00%> (ø)

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[crenshaw-dev]

/cherry-pick release-2.6

[crenshaw-dev]

/cherry-pick release-2.5

[crenshaw-dev]

/cherry-pick release-2.4