Limit spam checks to title, description, or confidentiality changes on bot-created issues

What does this MR do?

We have these two issues(#227755 (closed), #220297 (closed)) where users are getting stuck with reCaptcha spam checks when making updates to sidebar fields (milestones, labels, weights, etc.) This especially impacts Service Desk issues as they are created by bots, and issues authored by bots always get sent through the spam check.

This MR updates the check on bot-authored issues to only spam check when title, confidential state, or description are updated (which is the same conditions we apply to all issues (seen here: https://gitlab.com/gitlab-org/gitlab/blob/220297-attempts-to-edit-issue-are-blocked-by-never-ending-captchas/app/models/issue.rb#L357-360)

This should improve the situation for Service Desk users who are frequently getting stuck.

Does this MR meet the acceptance criteria?

Conformity

Availability and Testing

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