Use uprobestats_mainline_flags_java_lib_test_host in tests

Uprobestats now has a read/write flag, requiring the flags lib being
broken up for regular target vs host side tests.

Bug: N/A
Test: TH
Flag: EXEMPT test only
Change-Id: I40e5d3f3549c68aaef6bbd9219d1e14f2d6a4e56