Allow for Git's quarantine directories in quarantine path validation

When getting a repository's object directory, we're checking the directory points to a path we expect. We've allowed for random quarantine directories of transactions by checking whether the path ends with a /quarantine suffix. This is not sufficient as Git push may further apply its own quarantine in the transaction's quarantine directory that looks someting like /quarantine/tmp_objdir-incoming-Gbc29N. Adjust the check to allow for both kinds of paths.

It's debatable whether validating the quarantine path specifically here is very useful given we don't validate in most other places. For now, let's keep the existing validation logic in place though.

Closes #6017 (closed)