Have BC use default provider rather than always BC

In cases where BC algorithms need access to other algorithms, switch to
using the default implementation of JCA algorithms rather than always
using the BC version.  Some non-deprecated BC algorithms can access
deprecated BC implementations by using this scheme, and in general we want
to use Conscrypt algorithms when available.

Also comment out a class that isn't ever used.

Bug: 68057944
Test: cts -m CtsLibcoreTestCases
Test: cts -m CtsKeystoreTestCases
Change-Id: Iec4f395b0c6c59865ff6179a4edd3124d2967da9
6 files changed