Delete several DH key tests

The Bouncy Castle upgrade added a subclass of DHParameterSpec that
includes more information about the key parameters.  There's no reason
to bar extending those classes, so we no longer need the assertion
that it's precisely the base class.  Once that's gone, the rest of the
assertions are largely just testing the signatures of the methods, so
we can just delete the test cases entirely.

Test: cts -m CtsLibcoreTestCases -t org.apache.harmony.crypto.tests.javax.crypto.interfaces
Change-Id: I4f69a7527d7f5eace1c3bbaf662cb9d584c28f5b
2 files changed