tests: Make sure the port group is not hardcoded

The port group name consists of DP key and NB PG name.
Use first PG that is avaiable to avoid flakes when
neither of the logical switches has DP key 2.

Signed-off-by: Ales Musil <amusil@redhat.com>
Acked-by: Mark Michelson <mmichels@redhat.com>
Signed-off-by: Mark Michelson <mmichels@redhat.com>

tests/ovn.at

@@ -32491,9 +32491,9 @@ AT_CHECK([test $(ovs-ofctl dump-flows br-int table=46 | grep conjunction | wc -l
 
 for i in $(seq 1 10); do
     # Delete and recreate the SB PG with same name and content.
-    sb_pg_name=2_pg1 # dp key + NB pg name
+    sb_pg_name=$(fetch_column port_group name | cut -d ' ' -f1)
     sb_pg_uuid=$(fetch_column port_group _uuid name=$sb_pg_name)
-    ports_=$(fetch_column port_group ports name=2_pg1)
+    ports_=$(fetch_column port_group ports name=$sb_pg_name)
     ports=${ports_/ /,}
     AT_CHECK([ovn-sbctl destroy port_group $sb_pg_uuid -- create port_group name=$sb_pg_name ports=$ports], [0], [ignore])