gitaly: Don't wrap `updateref.ErrInvalidReferenceFormat`
requested to merge 4797-flaky-test-testtransactionmanager-invalid_reference_aborts_the_entire_transaction-flaky-2 into master
In prepareReferenceTransaction we first call updater.Update and then
updater.Prepare. In updater.Prepare we check for
updateref.ErrInvalidReferenceFormat and if found, we wrap it with
gitaly.InvalidReferenceFormatError.
This is flaky, since we don't check for the same in updater.Update.
Since the error from git can occur in either the Update or Prepare
stage, we could end up with either updateref.ErrInvalidReferenceFormat
or gitaly.InvalidReferenceFormatError. Let's fix this racy-flake by
just relying and testing for updateref.ErrInvalidReferenceFormat.
Closes #4797 (closed)