RFR(XS): 8208704: runtime/appcds/MultiReleaseJars.java timed out often in hs-tier7 testing

[Calvin Cheung]

bug: https://bugs.openjdk.java.net/browse/JDK-8208704
webrev: http://cr.openjdk.java.net/~ccheung/8208704/webrev/

Please review this small test fix:
- increase the timeout to 2400;
- reduce the test output by removing the -verbose:class option since the 
class loading output isn't being inspected for this test.

thanks,
Calvin