Exclude Project bot users from licensing

Topic to Evaluate

• Link to parent Issue

Tasks to Evaluate

• Technical evaluation: Determine if the newly added Task Bot users are counted in license - Yes
• If yes, add changes to exclude them as part of the Acceptance Criteria for Task bot users. - Included below.
• If no, sit back and relax ☺

Acceptance Criteria

Exclude project bot users from licensing:

• For self-managed - Done as part of previous MR: https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/app/models/ee/user.rb#L272
• For GitLab.com - Requires update on billable_user_ids: https://gitlab.com/gitlab-org/gitlab/-/blob/923dc54cb7f48540f8128bbfdcf39d54bce36881/ee/app/models/ee/group.rb#L259