update process running test case for dhcpcd
Summary:
With D40090857 landed, ifupdown will start the dhcpcd with both IPv4 and IPv6.
Update the Process Running test case.
Test Plan:
Build test with QEMU
```
root@bmc-oob:~# python3 /tmp/tests2/cit_runner.py -s /tmp/tests2 --platform grandcanyon -r tests.grandcanyon.test_process_running
test_installed_processes (tests.grandcanyon.test_process_running.ProcessRunningTest) ... ok
----------------------------------------------------------------------
Ran 1 test in 0.220s
OK
```
Reviewed By: doranand
fbshipit-source-id: 522dd3567ab45c75932f47c09d95fef5a09cfbb2
