Update vmTestbase/nsk/share/LocalProcess.java to don't use finalization

The vmTestbase/nsk/share/LocalProcess.java is a wrapper for debuggee process. It extends FinalizableObject to kill the debuggee process.

The debuggee process is used by nsk.jdb tests only, see runTest(...) in vmTestbase/nsk/share/jdb/JdbTest.java:
https://github.com/openjdk/jdk/blob/master/test/hotspot/jtreg/vmTestbase/nsk/share/jdb/JdbTest.java#L189

I verfied that process is always already terminated when is cleaned during VM shutdown hook,
So the fix is just to remove the finalization.

I also moved LocalProcess into nsk.share.jdb to reduce visibility of class and hardened checks in runTest.