8008964: NPG: Memory regression: Thread::_metadata_handles uses 1 KB per thread.

Summary: Reduce default size of Thread::_metadata_handles from 300 to 30
Reviewed-by: coleenp, sspitsyn

src/share/vm/runtime/thread.cpp

@@ -220,7 +220,7 @@ Thread::Thread() {
   set_osthread(NULL);
   set_resource_area(new (mtThread)ResourceArea());
   set_handle_area(new (mtThread) HandleArea(NULL));
-  set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(300, true));
+  set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
   set_active_handles(NULL);
   set_free_handle_block(NULL);
   set_last_handle_mark(NULL);