Move `no_touching` to `CommonSystemNotesService`

What does this MR do?

Since we always want to wrap this in ActiveRecord::Base.no_touching, I moved this inside the service so that we don't forget to do that.

There was a problem in specs for Rails 6 because the calls to the service in the specs are not wrapped in ActiveRecord::Base.no_touching. Updating the noteable caused the dirty tracking to reset and some specs to fail.

This I think is also better design so I went with this refactor.

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

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

#31034 (closed)