Remove references to nonexistent feature flag

What does this MR do?

Apparently the g_compliance_dashboard_feature never existed. It was used as an example in documentation and test coverage, so a YAML file was created for it as if it was an actual feature flag. This deletes that YAML file and replaces all references with actual feature flag names. This should avert future confusion.

This MR was prompted by #251080 (closed).

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.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

Related to #251080 (closed)