Closes #41633

When a project uses fast-forward merging strategy user has
to rebase MRs to target branch before it can be merged.
Now user can do rebase in UI by clicking 'Rebase' button
instead of doing rebase locally.

This feature was already present in EE, this is only backport
of the feature to CE. Couple of changes:
* removed rebase license check
* renamed migration (changed timestamp)

Closes #40301

Signed-off-by: Rémy Coutable <remy@rymai.me>

Rake doesn't respect eager-loading, so to avoid explicit requires we have to
duplicate the eager-load config into the auto-load config.

This backports an EE change made in https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/3706

I've followed the [upgrade guide](https://github.com/thoughtbot/factory_bot/blob/4-9-0-stable/UPGRADE_FROM_FACTORY_GIRL.md

) and ran these two commands:

```
grep -e FactoryGirl **/*.rake **/*.rb -s -l | xargs sed -i "" "s|FactoryGirl|FactoryBot|"
grep -e factory_girl **/*.rake **/*.rb -s -l | xargs sed -i "" "s|factory_girl|factory_bot|"
```

Signed-off-by: Rémy Coutable <remy@rymai.me>