runner: Disable socket communications for now

Currently, having i915 CI systems test the socket communications when
testing is impossible. If a test hangs completely, the incomplete set
of results are processed into results.json with an older IGT version
from a previous post-merge build, which is unable to parse socket
communications. Disable them for now.

This commit will get reverted after suitable testing has been possible
to execute.

v2: Rename the enable var, explain its presence further in a comment
    (Kamil)

Signed-off-by: Petri Latvala <petri.latvala@intel.com>
Acked-by: Kamil Konieczny <kamil.konieczny@linux.intel.com>