GitLab integration deletion does not remove asset connections

When I delete a GitLab integration from the organization settings, the connections of assets that are already linked to this integration are not removed. Deleting the integration should also remove these asset connections.

Steps to reproduce

1. Connect an asset to a GitLab integration in the organization settings.
2. Delete the GitLab integration.
3. Observe that the asset connection to the deleted integration still exists.

I think this is also the same behavior for other integrations, such as GitHub or Jira.

Start by tracing the organization-settings handler for deleting a GitLab integration and the persistence logic for asset connections. Reproduce the three steps described, then verify that deleting the integration removes its existing asset connections; check whether the same behavior applies to GitHub or Jira integrations.