Use commit and branch ref validation for release in CI config

What does this MR do?

Use Commit.reference_valid? and Gitlab::GitRefValidator.validate to check ref in the release node of the CI configuration.

Per the Releases API docs a ref can be a commit SHA, another tag name, or a branch name:

If tag_name doesn’t exist, the release will be created from ref. It can be a commit SHA, another tag name, or a branch name.

This feature is still behind the ci_release_generation feature flag so it's safe to make this change.

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.
• 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

Closes #227116 (closed)