Do not move deletionTimestamp to the future

[liggitt]

What type of PR is this?
/kind bug

What this PR does / why we need it:
API doc for the deletionTimestamp field indicates that once a value is set, it may not be moved into the future. However, the generic store does that.

Which issue(s) this PR fixes:
Fixes #73098

Does this PR introduce a user-facing change?:

metadata.deletionTimestamp is no longer moved into the future when issuing repeated DELETE requests against a resource containing a finalizer.

/sig api-machinery

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: liggitt

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• staging/src/k8s.io/apiserver/OWNERS [liggitt]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[liggitt]

/retest

[liggitt]

/retest

[dims]

/lgtm

[danielqsj]

/lgtm

[rcernich]

Any plans to back port the fix for this to older versions? I'm using a conflict error loop to account for this in my operator (which adds a finalizer to a customer resource), but the window for retry is pretty small (looks like there's a 1s delay between syncs in the namespace controller, so 1s to get current instance, remove finalizer, update) and I'm concerned it may still fail intermittently.