Use only one core on fugu by default.

Make the current buildbot setting the default so
that we can remove the setting from the buildbot.

Test: "testrunner.py --host" and check the concurrency
Test: "testrunner.py --target" and check the concurrency
Change-Id: I0293d00e7ace1087341a387802a1b2bfeb1cb719
1 file changed