TestKeyStore: add the ability to set certificate serial numbers

Change URLConnectionTest#testHttpsWithCustomTrustManager
to check for specifically set serial numbers.

As of 5a85130cc3ee3df65c3b263773e3649277b37317, the serial numbers
were being generated randomly, and the test was looking for the
value "1", so the test was broken.

Bug: 27987415
Change-Id: I1b6a8dbcb496808266f66ede9503027ab8693861
2 files changed