Fix reload_config failed on M0 device because PFCWD feature does not …

…exist (sonic-net#14138)

Fix reload_config failed on M0 device because PFCWD feature does not exist

#### Why I did it
test case test_fallback_to_local_authorization_with_config_reload failed on M0 device when reload config.
It's because PFCWD feature does not exist on M0.

### How I did it
Ignore check when PFCWD feature not enable on device.

#### How to verify it
Pass all test case.

### Description for the changelog
Fix reload_config failed on M0 device because PFCWD feature does not exist

tests/common/config_reload.py

@@ -105,6 +105,12 @@ def config_reload_minigraph_with_rendered_golden_config_override(
                   override_config=True, golden_config_path=golden_config_path, is_dut=is_dut)
 
 
+def pfcwd_feature_enabled(duthost):
+    device_metadata = duthost.config_facts(host=duthost.hostname, source="running")['ansible_facts']['DEVICE_METADATA']
+    pfc_status = device_metadata['localhost']["default_pfcwd_status"]
+    return pfc_status == 'enable'
+
+
 @ignore_loganalyzer
 def config_reload(sonic_host, config_source='config_db', wait=120, start_bgp=True, start_dynamic_buffer=True,
                   safe_reload=False, wait_before_force_reload=0, wait_for_bgp=False,
@@ -195,7 +201,8 @@ def _config_reload_cmd_wrapper(cmd, executable):
         pytest_assert(wait_until(wait + 300, 20, 0, sonic_host.critical_services_fully_started),
                       "All critical services should be fully started!")
         wait_critical_processes(sonic_host)
-        if config_source == 'minigraph':
+        # PFCWD feature does not enable on some topology, for example M0
+        if config_source == 'minigraph' and pfcwd_feature_enabled(sonic_host):
             pytest_assert(wait_until(wait + 300, 20, 0, chk_for_pfc_wd, sonic_host),
                           "PFC_WD is missing in CONFIG-DB")