Remove the old CompOS key management

We no long persist keys on behalf of CompOS, so a lot of code is
redundant and can be removed.

Bug: 218494522
Test: Run staged-compile, reboot & watch odsign
Merged-In: Ia649165630048a3b625e6c7aa84e8b5d18d2a8da
Change-Id: Ia649165630048a3b625e6c7aa84e8b5d18d2a8da
1 file changed