Add option to trigger webhooks only after Geo replication has completed

Description

Replication is typically near instantaneous, but it is possible to have a secondary (mirror) out of sync if the change is large, or the background queue is full. We are using the GitLab Jenkins plugin, which relies on webhook functionality, which is configured on the GitLab primary, with Jenkins configured to clone from a GitLab secondary server.

Proposal

Add an option to only trigger a webhook/integration after the primary has pushed to all secondaries. It would be useful for push events at a minimum.