Toggling GitLab Integration settings change the type of content that is being posted to GitLab
Customizing GitLab Integration
Merge Requests Comment - will toggle on / off posting run results summary to a merge request
Commit Status - will toggle on / off updating commit status with run results
Disabling GitLab Integration
Clicking Disconnect Project (1) will detach the integration from the currently selected GitLab project. Disconnecting a project would keep GitLab OAuth App credentials. You would still be able to select a different GitLab project from the list to reactivate the integration.
Uninstalling (2) the integration removes the associated credentials and the integration altogether.