Revert "disabled_oauth_sign_in_sources column" and keep on schema only the disabled_oauth_sign_in_sources column

This reverts commit 95358e0095403ad44149d11922d52e4590285a20.

This reverts commit 78a832d0fd7ff445c707809134dbb2a42d2a9e03.

Show help only for the enabled OAuth Providers on oauth-providers-help block

aria: { describedby: help_block_id } instead of 'aria-describedby' => help_block_id

provider and not p

a more simple approach to the OmniAuth helper links for oauth-providers-help

Allow Admins to remove the Login with buttons for OAuth services and still be able to import on the changelog

On Application Settings Page let the user select the enabled OAuth Sign in sources instead of the disabled ones

if omniauth is enabled and if there are button_based_providers available show the disable OAuth sources

stub Devise.omniauth_providers to return GitHub even if the gitlab.yml has no omniauth provider enabled
This will fix failing tests in case gitlab.yml file has no omniauth providers enabled

Update 8.8 guides

See merge request !4119

Relative Links in the Wiki Are Broken

- [ ] #16568 (!4050) Relative links in wiki are broken
    - [x] Investigate issue

  
    - [x] Implementation / Fix

        - [x] Write (failing) tests for `WikiLinkFilter`
        - [x] Link to `./bar` should either get rewritten correctly or left alone
        - [x] Link to `./bar.md` should maybe get rewritten correctly (is left alone currently)
        - [x] Link to `bar.md` should get rewritten correctly


            - [x] Check if this indeed a bug

    - [x] Make sure CI is green
    - [x] Assign to endboss

    - [x] Wait for review

    - [x] Implement review feedback
    - [ ] Wait for merge


See merge request !4050