bsdinstall services: Improve mouse configuration

bsdinstall(8) has an option to enable moused support.
However, if it is not selected, moused is still started
through the configuration of nondefault devices.
So, automatically add the moused_nondefault_enable="NO"
setting to rc.conf unless moused support is selected.

PR: 227999
Reported by: bcran
Reviewed by: bapt
Differential Revision: https://reviews.freebsd.org/D35193