Using the sed script from
https://gitlab.com/gitlab-org/gitlab-ce/issues/59758

Replaced Settings with Gitlab.config for uniformity

Pool repositories are persisted in the database, and when the DB is
restored, the data need to be restored on disk. This is done by
resetting the state machine and rescheduling the object pool creation.

This is not an exact replica of the state like at the time of the
creation of the backup. However, the data is consistent again.

Dumping isn't required as internally GitLab uses git bundles which
bundle all refs and include all objects in the bundle that they require,
reduplicating as more repositories get backed up. This does require more
data to be stored.

Fixes https://gitlab.com/gitlab-org/gitaly/issues/1355

Partially addresses #47424.

Had to make changes to spec files because
stubbing methods on frozen objects is a mess
in RSpec and leads to failures:

https://github.com/rspec/rspec-mocks/issues/1190

Moved to OPT_OUT in 7d14b725a0da41d1ae7c0a8496b5e66832023e3b, Now, by
removing the feature gates, this is an mandatory feature.

Related issues:
- https://gitlab.com/gitlab-org/gitaly/issues/526
- https://gitlab.com/gitlab-org/gitaly/issues/1194

Closes https://gitlab.com/gitlab-org/gitaly/issues/749
Closes https://gitlab.com/gitlab-org/gitaly/issues/1212
Closes https://gitlab.com/gitlab-org/gitaly/issues/1195