Fix AssumptionViolatedException usage with JUnit3

Junit3 does not properly handle AssumptionViolatedException.
Skip tests in JUnit3,  explicitly use Junit4 where possible

Also improved the error messages.

Bug: 185269177
Test: atest DecoderTestXheAac MediaMetadataRetrieverTest
Change-Id: I7a46098aa5d137f3f7040c768b477b4c49438652
Merged-In: I7a46098aa5d137f3f7040c768b477b4c49438652
(cherry picked from commit fb3ad7df90cf0d13246f6cfa7218f82d033b5714)
3 files changed