You cannot change the database connection for the jobs because the jobs does not get it connection parameters from the TAC instead it comes from a dedicated database connection metadata and mostly also from a context var group.
The TAC has a database connection to configure the reading amc web app.
I would strongly suggest to separate the production TAC from the development TAC. It is far from being reliable of you run the production within the development. You can install TAC (and all other servers) as much as you want because Talend typically delivers named user licenses and this license does not care about the amount of installations.
I would suggest using separate server hardware for development and production (even better also for test).