Add `databaseTasks: boolean` to `gitlab.psql.` config

What does this MR do?

Some databases configured (ci:) if they do share the host/port/database with main: should rather have database_tasks: false to be configured. This makes such configurations to not be managed by GitLab Rails for the purpose of creating databases or migrating them.

This implements databaseTasks: attribute that is inherited as all other attributes that can be configured to any value.

The default is databaseTasks: true. This similar to gitlab-org/omnibus-gitlab!5982 (merged) if detects that host/port/database equals to main it will automatically set it to false.

If the host is not equal, but still points to the same database admin should configure databaseTasks: false by themselves.

Disclaimer: The presence of the database_tasks: without a backport (gitlab-org/gitlab!82902 (merged)) is no-op, so it is safe. Backport was merged.

Disclaimer: I do not have GitLab Helm configured, so only validations that I did perform is running modified specs with helm installed.

Related issues

gitlab-org/gitlab#356009 (closed)

Checklist

See Definition of done.

For anything in this list which will not be completed, please provide a reason in the MR discussion.

Required

• Merge Request Title and Description are up to date, accurate, and descriptive
• MR targeting the appropriate branch
• MR has a green pipeline on GitLab.com

Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes
• Documentation created/updated
• Tests added
• Integration tests added to GitLab QA
• Equivalent MR/issue for omnibus-gitlab opened