Update test SuspendWithCurrentThread.java to verify that suspend doesn't exit until resumed

Test test/hotspot/jtreg/serviceability/jvmti/SuspendWithCurrentThread/SuspendWithCurrentThread.java

tries to suspend the thread list which includes the current thread. However, it suspends and resumes list under the same agent_monitor lock.

The test really should hang. See fix in loom:
https://github.com/openjdk/loom/commit/c088b36d0e94fe7527239f716754d395675d3e1e

The test should be updated in a similar way. Also, it should check that resume is actually called before test continue execution after suspend.