Let Gitlab/RailsLogger check only log methods

What does this MR do?

This MR tweaks Gitlab/RailsLogging 👮 to check only the log methods (:info, :warn etc) allowing other methods like Rails.logger.level for historical reasons.

See #247092 (closed) for more context.

This MR also utilizes RuboCop's configuration option Exclude: avoiding the programmatic version removing a misused term from the codebase.

📣 Please don't squash the commits!

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