Make cts JVMTI tests more consistent

Make a dex file version test use an in-memory dex file so it's not
affected by build system changes in test 912.

Make sure we filter out the InstrumentationInstallThread in test 911.

(cherry picked from commit 88df35c3)

Test: ./test.py --host -j50
Test: cts-tradefed run cts-dev --module CtsJvmtiRunTest911HostTestCases
Test: cts-tradefed run cts-dev --module CtsJvmtiRunTest912HostTestCases
Bug: 66681249
Merged-In: Ibee880730df7178a3fa6248fb73f4198b6374b91
Change-Id: Ibee880730df7178a3fa6248fb73f4198b6374b91