Add cop to prevent index creation on forbidden table

Ref: #332886 (closed)

What does this MR do?

This MR adds a new custom cop allowing us to prevent index creation on a given table.

The first table forbidden targeted is ci_builds and will only affect new code being added.

Why are we doing this?

As part of Reducing number of indexes on ci_builds table, we should prevent adding new indexes to this table.

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?)
• [-] 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.