updated the test case to disable the service directly (#2577)

Use systemctl stop teamd instead of config feature.
Changes trigger because of sonic-net/sonic-buildimage#6000

tests/pc/test_po_cleanup.py

@@ -51,7 +51,7 @@ def test_po_cleanup(duthosts, rand_one_dut_hostname):
 
     try:
         logging.info("Disable Teamd Feature")
-        duthost.shell("sudo config feature state teamd disabled")
+        duthost.shell("sudo systemctl stop teamd")
         # Check if Linux Kernel Portchannel Interface teamdev are clean up
         if not wait_until(10, 1, check_kernel_po_interface_cleaned, duthost):
             fail_msg = "PortChannel interface still exists in kernel"