Rails 6.0.3.1 Take 2

What does this MR do?

Rails 6.0.3.1 - https://weblog.rubyonrails.org/2020/5/18/Rails-5-2-4-3-and-6-0-3-1-have-been-released/

Commit 1

(reverted in !33446 (merged), previously approved in !32486 (merged)

Commit 2

Patch to generate 6.0.3 tokens so that we do not have CSRF errors while rolling out 6.0.3.1. This enables GitLab to have a mix of 6.0.3 and 6.0.3.1 Rails servers

1. Deploy this patch with :global_csrf_token FF disabled.
2. Once all Rails servers are on 6.0.3.1, enable :global_csrf_token FF.
3. On GitLab 13.2, remove this patch (!35104 (merged))

Related issue: #219576 (closed)

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.