Clean up application settings Tofa config

What does this MR do and why?

As per documentation, we're dropping the columns.

This MR is follow-up from Clean up tofa* db columns (!121205 - merged)

Here, we are cleaning-up TOFA related settings. Partially addresses https://gitlab.com/gitlab-org/gitlab/-/issues/408829+

Screenshots or screen recordings

N/A

How to set up and validate locally

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