[Rock-ons] Failure to detect rock-ons using host networking

[FroggyFlox]

One of the features intended in #2207 was to detect the rock-ons with container(s) using host networking so that we disable the Networking customization options accordingly. Unfortunately, the underlying logic was lost during #2207's development and we now fail to accurately detect such rock-ons.

As mentioned in #2239 (comment), the culprit is the following line...

rockstor-core/src/rockstor/system/docker.py

Lines 152 to 153 in 1223360

	if container:
	cmd.extend((running_filters + ["--filter", "name={}".format(container),]))

... in which the running_filters shouldn't be applied there. Indeed, these are intended to detect running rock-ons, which shouldn't be used here and is in contradiction with the all=True flag that we need instead (and use).

It has also become evident we need to establish unit test coverage of system/docker.py to catch such problems/regressions.