Update Slack channel references from g_delivery to g_release_and_deploy
Updates all references to the #g_delivery Slack channel to #g_release_and_deploy across the documentation.
Related to https://gitlab.com/gitlab-com/gl-infra/delivery/-/issues/21527
Files updated:
general/slack-automated-response.mdgeneral/security/utilities/merge_train.mdgeneral/security/how_to_sync_security_with_canonical.md
Edited by Dave Smith