Automate the creation of database roles and objects for new-empty databases

We need to automate the creation of roles when deploying a new empty database as it was the case of the Embedding Database for AI experiments https://gitlab.com/gitlab-com/gl-infra/reliability/-/issues/23472 (related to https://gitlab.com/gitlab-com/gl-infra/reliability/-/issues/23514)

The following components require users/roles and objects to be created:

• pgbouncer DB roles and objects - the manual process seems to be the one found at delivery#2024 (comment 677171253)
• gitlab_exporter
• Teleport (console) roles