Apply suggestions from code review

Co-authored-by: Tim Pillinger <26465611+wxtim@users.noreply.github.com>

Author: wxtim

cylc/flow/scripts/cylc.py

@@ -586,7 +586,6 @@ def pycoverage(cmd_args):  # pragma: no cover
         cylc_wc = Path(os.environ['CYLC_COVERAGE_BASE'])
     else:
         cylc_wc = Path(cylc.flow.__file__).parents[2]
-    print(f'START: {sys.argv[1:]}', file=sys.stderr)
 
     # initiate coverage
     try:
@@ -608,9 +607,7 @@ def pycoverage(cmd_args):  # pragma: no cover
             '\n\n*****************************\n\n'
         ) from exc
 
-
     def cov_stop(*a, **k):
-        print(f'STOP: {sys.argv[1:]}', file=sys.stderr)
         cov.stop()
         cov.save()
         if cylc_coverage == '2':
@@ -630,6 +627,7 @@ def cov_stop(*a, **k):
         # stop the coverage and save the data
         cov_stop()
 
+
 def get_arg_parser():
     parser = argparse.ArgumentParser(add_help=False)
     parser.add_argument(