### Problem to solve We already have chat notifications for successfull/canceled/failed deployments for slack, mattermost, etc... But not for starting deployments. Notifications for starting deployments might be valuable, e.g. as warning that something is happening with production infrastructure right now. ### Proposal Add notification about starting deployments to chat integrations. ### Note It's highly coupled with https://gitlab.com/gitlab-org/gitlab/-/issues/235474, so it will take less effort to work on these 2 issues simultaneously.