Refactor Rails initializers
<!--IssueSummary start-->
<details>
<summary>
Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards.
</summary>
- [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=25845)
</details>
<!--IssueSummary end-->
We currently have 100+ initializers in `config/initializers`. These are loaded by Rails alphabetically so ordering is important.
We have a few of them that are numbered to force the order but they are inconsistent and there are duplicate numbers. `01_..`, `1_..`, etc..
This has caused a bug here: https://gitlab.com/gitlab-org/gitlab-ce/issues/55513
We should name these consistently and perhaps make it easier to insert initializers in between without having to rename a bunch of files.
We should also consider reducing the number of files here.
issue