8217659: monitor_logging updates from Async Monitor Deflation project Reviewed-by: dholmes, coleenp, rehn

8213753: SymbolTable is double walked during class unloading and clean up table timing in do_unloading Summary: remove gc timing for short runtime cleanup triggering; make symbol table cleaning triggered automatically on unloading Reviewed-by: shade, stefank, gziemski

8216072: Remove TaskTerminator's assignment operator Reviewed-by: tschatzl, rkennke, kbarrett