[Ravenwood] Always initialize Ravenwood environment

Even if no configuration or rules are set, we still want tests to run in
the default Ravenwood environment.

Test: $ANDROID_BUILD_TOP/frameworks/base/ravenwood/scripts/run-ravenwood-tests.sh
Flag: EXEMPT host test change only
Bug: 356918135
Change-Id: Ic065953881229c2e226f55db4db9fc46b1e0e08f
4 files changed