test: bring back userns testing
test: bring back userns testing

Commit 92caff26d ("Added EnvVar to cri-o cli flags", May 29 2019)
changed some testing code to use CONTAINER_{U,G}ID_MAPPING
instead of {U,G}ID_MAPPING environment variables, but a place
in test/test_runner.sh was omitted. This, I guess, resulted
in not testing userns (at least partially -- there are tests that enable
it explicitly rather through a TEST_USERNS env var).

Next, commit b80c31b9cf ("Allow CRI-O to manage IPC and UTS namespaces",
Dec 16 2019) changed the option ManageNetworkNSLifecycle to
ManageNSLifecycle, and changed its default to be true. Since this
commit, it is now needed to disable the option to allow userns testing
(otherwise we get "cannot use UIDMappings with ManageNSLifecycle"
error).

Finally, one can't set ManageNSLifecycle=false when DropInfraCtr=true
(or one will get "cannot drop infra without ManageNSLifecycle" error).

This commit fixes all three issues, bringing back userns containers
testing.

Signed-off-by: Kir Kolyshkin <3a017b8ddb3f9cf3e4a59978b004111bdeb97f08@gmail.com>

kubernetes-incubator/ocid,kubernetes-incubator/ocid,kubernetes-incubator/cri-o,nalind/cri-o,kubernetes-incubator/cri-o,kubernetes-incubator/ocid,kubernetes-incubator/cri-o,nalind/cri-o,kubernetes-incubator/cri-o,nalind/cri-o