Use swsscommon instead of swsssdk (sonic-net#1510)

#### What I did
Changed code to use use swsscommon instead of swsssdk in counterpoll

#### How I did it
Removed an explicit function call from sdsssdk module

#### How to verify it
run counterpoll tests

counterpoll/main.py

@@ -129,7 +129,7 @@ def disable():
 @click.pass_context
 def pg_drop(ctx):
     """  Ingress PG drop counter commands """
-    ctx.obj = swsssdk.ConfigDBConnector()
+    ctx.obj = ConfigDBConnector()
     ctx.obj.connect()
 
 @pg_drop.command()