VTS tests for fixed MediaDrm security level APIs

Vendors implementing the newly added MediaDrm.setSecurityLevel
HAL found that it was difficult to implement properly. Also the
semantics are somewhat ambiguous from the Java platform API
level. The APIs have changed to bind the security level
assignment to openSession which clarifies the API for apps as
well as making it more natural to implement in HAL modules. This
CL updates the VTS tests to account for those changes.

bug:72831697
bug:64001680

test: VtsHalDrmV1_1TargetTest, GTS media tests
Change-Id: I2adf13f9da7726b206df6fcc82b1e2e11fc94674