[TASK] Return to "Admin Tools > User Admin" when exiting simulated BE User

When exiting a simulated BE user, you return to the backend user module
instead of the default startup page.

Resolves: #22020
Releases: 6.2
Change-Id: I8de7b6f79e6ddb9bc03f62364f3246ef13a4ddf3
Reviewed-on: https://review.typo3.org/28689
Reviewed-by: Markus Klein
Reviewed-by: Philipp Gampe
Tested-by: Philipp Gampe
Reviewed-by: Stefan Neufeind
Tested-by: Stefan Neufeind