Switch back to nc in test_load_balancer_basic

After test_load_balancer_basic started using inetd instead of netcat
we've started getting "BadStatusLine" errors from urllib.

That is why we need to move back to using netcat.
Also handle "BadStatusLine" error.

Related bug: 1309252
Change-Id: Ida919c63e27c6a003be4c249ba2e6f3e2ea7a7b3
Merge "Switch back to nc in test_load_balancer_basic"