The previous "revert unrelated changes" commit rolled main's post-#2478
state back to pre-#2478, undoing the deprecated-Requeue-field cleanup
and the checkRequiredTags (bool, error) signature. Restore main's
current state for those call sites so this PR is limited to the
finalizer reorganization.

* [CONTP-1335] organizing finalizers initial PR

* reverted bug fix

* Fix HandleFinalizer deletion-path return and remove redundant caller guards

HandleFinalizer was missing a return on the deletion path, causing
reconciliation to continue into create/update logic. Remove the
compensating GetDeletionTimestamp checks from all 5 callers, fix SLO
deleteResource closure capture, and improve finalizer test coverage.

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

* added finalizer and error requeue periods

* fix: requeue after adding finalizer to match original controller behavior

HandleFinalizer was falling through after adding a finalizer instead of
requeuing, causing controllers to run create/update logic on the same
reconcile pass. This broke the datadogmonitor unsupported-type and
datadogslo create-failure test cases. Updated SLO tests to reconcile
twice (once for finalizer, once for actual logic).

* fix: use immediate requeue after adding finalizer for controllers that had Requeue:true

The old datadogagent, datadogagentinternal, datadogdashboard, and
datadoggenericresource controllers all used Requeue:true (immediate)
after adding a finalizer, while datadogmonitor/datadogslo used
RequeueAfter with a period. The shared HandleFinalizer now supports
both: pass 0 for immediate requeue, or a duration for delayed requeue.

This fixes the 34 integration test timeouts where the 60s requeue
delay exceeded the 10s test timeout.

* fix: use defaultErrRequeuePeriod for all controllers after adding finalizer

All migrated controllers now pass defaultErrRequeuePeriod (5s) as the
requeue period when adding a finalizer, consistent with the existing
datadogslo pattern. Removes the Requeue:true special case for zero
period from HandleFinalizer.

* refactor: simplify HandleFinalizer to use immediate requeue, revert unrelated changes

- Remove defaultRequeuePeriod param from NewFinalizer; HandleFinalizer
  now always uses immediate requeue (Requeue: true) after adding a
  finalizer or while waiting for deletion, matching the original behavior
  of most controllers.
- Revert result.IsZero() cleanup and checkRequiredTags signature refactor
  as they are out of scope for this ticket.

* fix: restore SA1019 cleanup from #2478 that was inadvertently reverted

The previous "revert unrelated changes" commit rolled main's post-#2478
state back to pre-#2478, undoing the deprecated-Requeue-field cleanup
and the checkRequiredTags (bool, error) signature. Restore main's
current state for those call sites so this PR is limited to the
finalizer reorganization.

* reinstated default requeue period and implemented deletion requeue period

* fixing naming inconsistency

---------

Co-authored-by: Claude Opus 4.6 (1M context) <[email protected]>