[Ravenwood] Enable PFD.getStatSize and cleanup implementation

Bug: 353521759
Flag: EXEMPT host side test change only
Test: $ANDROID_BUILD_TOP/frameworks/base/ravenwood/scripts/run-ravenwood-tests.sh
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:be940db4aacbb14f0abc35197b224bf197ddac4f)
Merged-In: I011f14bdefb041d6f75a5d4c1d729dc368528d09
Change-Id: I011f14bdefb041d6f75a5d4c1d729dc368528d09