repository: Fix test for voting in CreateRepositoryFromBundle on macOS

In TestCreateFromBundle_transactional we assert that the received transactional votes match some static hashes so that we're sure that they stay stable. This is breaking on macOS though: the second round of votes asserts that hashing on-disk contents of the repository results in a stable hash, but on macOS the on-disk contents are different because the default Git configuration contains some additional keys not present on other platforms.

Fix this issue by instead manually computing the expected hash by doing the hashing ourselves first. Like this we continue to verify that we do indeed hash the correct files in a deterministic order, but adapt to the system's actual contents of those files.

Closes #4292 (closed)