Merge branch 'jc/revert-ref-transaction-hook-changes'

Merge branch 'jc/revert-ref-transaction-hook-changes'

Revert the "deletion of a ref should not trigger transaction events
for loose and packed ref backends separately" that regresses the
behaviour when a ref is not modified since it was packed.

* jc/revert-ref-transaction-hook-changes:
  RelNotes: revert the description on the reverted topics
  Revert "fetch: increase test coverage of fetches"
  Revert "Merge branch 'ps/avoid-unnecessary-hook-invocation-with-packed-refs'"