feat: add env option SONIC_STOP_PROFILING to stop profiling on demands

[AsterDY]

what this PR for?

• as Panic: invalid pc-encoded table #310 mentioned, go traceback while calling native functions may cause sonic crash. Therefore we commit PR feat: stop sigprof while calling native #342 to prevent this ahead. However, it will make profiling results inaccurate, especially when sonic is heavily used.
• Thus, we add an environmental variant SONIC_STOP_PROFILING to control if StopProf feature should open, which only works when this variant is not empty