gitlab: move linux-user plugins test across to gitlab

gitlab: move linux-user plugins test across to gitlab

Even with the recent split moving beefier plugins into contrib and
dropping them from the check-tcg tests we are still hitting time
limits. This possibly points to a slow down of --debug-tcg but seeing
as we are migrating stuff to gitlab we might as well move there and
bump the timeout.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20201002103223.24022-1-alex.bennee@linaro.org>