Minimize property_contexts

The remaining entries are based on "adb root; adb getprop", and "adb
logcat | grep 'Access denied'".

Some processes try to access removed entries, resulting in denials to
default_prop. But it's enough to add them when we actually need them.

Bug: 191131624
Test: atest MicrodroidHostTestCases
Change-Id: I9159ff0d8c02dc9eaabfc31dfbf18c914a69bf72