Shorten testClearKeyPlayback to 25 seconds.

Many failures seem to be due to poor network connection, causing test to timeout.
Shorten the test to 25 seconds, same as the refactored GTS tests. This time is
sufficient to test the decryption path.

bug: 26917432
Change-Id: Iaee8a935a93bcbc0ac0624443f2f28ce19b66791
1 file changed