[Ravenwood] Add "--strip-mockito" to Ravenizer

In some situations, removing the Android device-side Mockito from test
dependencies is nearly impossible. To make these tests continue to
function on Ravenwood, make the Ravenizer tool remove all conflicting
classes and files from the final test jar.

Bug: 292141694
Flag: EXEMPT host test change only
Test: atest RavenwoodCoreTest
Test: $ANDROID_BUILD_TOP/frameworks/base/ravenwood/scripts/run-ravenwood-tests.sh
Change-Id: Icfb81dc3b30f06e94050ebdf7ec5bb53959fcc12