Merge "Retrieve hiddenapi-flags.csv from platform-bootclasspath" am: e1315fd487 am: d6c04afe57 am: 48f4d70fbb

Original change: https://android-review.googlesource.com/c/platform/cts/+/1674034

Change-Id: Ia0bd4f993afb271055f75ed89933e5d4c81ec425