MFC r286368: Remove guards around overwriting loader.rc and menu.rc

There have been .local version of each for user modifications for some time
This allows users to receive future updates to these files

PR: 183765
Differential Revision: https://reviews.freebsd.org/D3176
Submitted by: Bertram Scharpf, Nikolai Lifanov (patch)
Reviewed by: dteske, loos, eadler
Approved by: bapt (mentor)
Relnotes: yes
Sponsored by: ScaleEngine Inc.