No need to test "GCM" mode in regular Cipher test

Partially revert change from 6e0cdd08e2a671393b8a410690d28140a80d9387.
Since the regular cipher test expects to be able to use all padding
types with every mode, testing GCM is not appropriate here.  It is
still tested elsewhere in CipherTest.

(cherry picked from commit a174063b24e6f792fc58373439808842e1c0d657)

Bug: 21209499
Change-Id: Ie20ddab4112f350cce08114c913a89a659823823
1 file changed