Filter out SIGTERM and SIGKILL exit codes from "completed almost ontime"

(cherry picked from commit 07e3b08)

exec_helpers/subprocess_runner.py

@@ -148,7 +148,7 @@ def close_streams():  # type: () -> None
             # Force stop cycle if no exit code after kill
         except OSError:
             exit_code = async_result.interface.poll()
-            if exit_code is not None:  # Nothing to kill
+            if exit_code is not None and exit_code not in {-9, -15}:  # Nothing to kill
                 self.logger.warning(
                     "{!s} has been completed just after timeout: please validate timeout.".format(command)
                 )