Stop deleting reserve copy file for permission and role

In the case of successive sudden reboots, a write to the original file
may be interrupted again, and we should keep using an existing reserve
copy.

Bug: 324004645
Flag: EXEMPT bugfix
Test: presubmit
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:306f27c036d2c1ead2033b0595081d39b05e9c06)
Merged-In: I982e23a4117cafae6fcfe2bac8f0531e8b72399c
Change-Id: I982e23a4117cafae6fcfe2bac8f0531e8b72399c