Rename a couple things to reduce confusion

- "ClassFilter" was confusing because we already use the word "filter" for something else.
Changed it to "ClassPredicate".

- "framework-policy-override.txt" was confusing because it's not actually for the
real framework code. It's only for the "test framework" classes.

Flag: EXEMPT host test change only
Bug: 292141694
Test: $ANDROID_BUILD_TOP/frameworks/base/ravenwood/scripts/run-ravenwood-tests.sh
Change-Id: Ic93f7e7516aea74b70d3b46a324552a25f93ab7a