Revert "Use RoSystemFeatures API where appropriate"

This reverts commit 6295552d because it
is not compatible with the mocking done by WeakEscrowTokenTests, causing
these tests to fail on Cuttlefish phone.  (The failure started not at
that commit, but rather when ag/33559128 turned the RoSystemFeatures
check into a build-time check.)

Test: atest FrameworksServicesTests:WeakEscrowTokenTests
Test: atest FrameworksServicesTests:com.android.server.locksettings
Bug: 418862901
Flag: TEST_ONLY
Change-Id: I149ea5d2bed958b66631e226ca9695fd8a51b065