auto-devops: support deploy freezes

What does this MR do?

Deploy Freezes are a useful tool to make sure deployments to production are blocked during a certain timeframe. The downside now, is if you're using Auto DevOps you'd need to overrule all rollout x% etc. jobs if you'd like to adhere to the deploy freezes.

How to setup and validate locally (strongly suggested)

1. Set a deploy freeze (be careful, they cannot be deleted yet) on an Auto DevOps project
2. Verify a commit does not trigger the production jobs

Does this MR meet the acceptance criteria?

Conformity

• I have included changelog trailers, or none are needed. (Does this MR need a changelog?)
• I have added/updated documentation, or it's not needed. (Is documentation required?)
  • Users now expect Auto DevOps to do the right thing out of the box, so adhering to Deploy Freezes seems like an intuitive thing.
• I have properly separated EE content from FOSS, or this MR is FOSS only. (Where should EE code go?)
• I have added information for database reviewers in the MR description, or it's not needed. (Does this MR have database related changes?)
• I have self-reviewed this MR per code review guidelines.
• This MR does not harm performance, or I have asked a reviewer to help assess the performance impact. (Merge request performance guidelines)
• I have followed the style guides.
• This change is backwards compatible across updates, or this does not apply.

Availability and Testing

• I have added/updated tests following the Testing Guide, or it's not needed. (Consider all test levels. See the Test Planning Process.)
• I have tested this MR in all supported browsers, or it's not needed.
• I have informed the Infrastructure department of a default or new setting change per definition of done, or it's not needed.