snyk: skip writing of scan metadata when no supported project

Reproducer: csmock -r rhel-9-x86_64 -t snyk -f octavia-amphora-image-vert-fips-x86_64-18.0-20240305.1.el9ost.src.rpm

Related: https://issues.redhat.com/browse/OSH-583

When an snyk-unsupported project is scanned using snyk, no stats are generated.

py/plugins/snyk.py

@@ -184,8 +184,9 @@ def scan_hook(results, mock, props):
  if ec == 3:
  # If there are no supported project, we return no results but no crash.
  results.print_with_ts("snyk-code: no supported project for Snyk")
- # If no supported project, no results file is generated
+ # If no supported project, no results file is generated and no stats are generated
  props.copy_out_files.remove(SNYK_OUTPUT)
+ props.post_process_hooks.remove(write_snyk_stats_metadata)
  return 0
  if ec not in [0, 1]:
  results.error("snyk code returned unexpected exit status: %d" % ec, ec=ec)