Update swss_ready check to check per namespace swss service (sonic-net#1974)

What I did
fixes sonic-net#9411
on multi-asic platform, config reload CLI was not working without -f option.
This was because swss_ready function was checking status of swss.service and multi-asic platform will not have swss.service, it will have per-namespace swss service.

How I did it
Fix swss_ready function to check all swss services status running on the platform.

Author: SuvarnaMeenakshi

config/main.py

@@ -767,18 +767,34 @@ def _delay_timers_elapsed():
             return False
     return True
 
-def _swss_ready():
-    out = clicommon.run_command("systemctl show swss.service --property ActiveState --value", return_cmd=True)
+def _per_namespace_swss_ready(service_name):
+    out = clicommon.run_command("systemctl show {} --property ActiveState --value".format(service_name), return_cmd=True)
     if out.strip() != "active":
         return False
-    out = clicommon.run_command("systemctl show swss.service --property ActiveEnterTimestampMonotonic --value", return_cmd=True)
+    out = clicommon.run_command("systemctl show {} --property ActiveEnterTimestampMonotonic --value".format(service_name), return_cmd=True)
     swss_up_time = float(out.strip())/1000000
     now =  time.monotonic()
     if (now - swss_up_time > 120):
         return True
     else:
         return False
 
+def _swss_ready():
+    list_of_swss = [] 
+    num_asics = multi_asic.get_num_asics()
+    if num_asics == 1:
+        list_of_swss.append("swss.service")
+    else:
+        for asic in range(num_asics):
+            service = "swss@{}.service".format(asic)
+            list_of_swss.append(service)
+
+    for service_name in list_of_swss:
+        if _per_namespace_swss_ready(service_name) == False:
+            return False
+
+    return True 
+
 def _is_system_starting():
     out = clicommon.run_command("sudo systemctl is-system-running", return_cmd=True)
     return out.strip() == "starting"