Remove build system dependency on external /zdw/ resources

A few problem workarounds have been deployed over time in the form of static python libraries hosted externally from github.  The need for these workaround (python v3.5 <=> v3.6) are no longer needed and dependencies should be weakened and removed.

Long term static libs will contribute to two problems:

• Frozen code base – some build system logic is anchored to python v3.5.
• Failure mode for makefile targets while offline.  Modules are explicitly retrieved to create a virtual env, this is a failure condition while working offline.
• python 3.10.X is unusable

Remove / weaken deps on:

• git+https://github.com/zdw/robotframework-importresource@b81b87aabaee0594e966687b41e3674b866f28ee
• git+https://github.com/zdw/robotframework-importresource@b81b87aabaee0594e966687b41e3674b866f28ee

Affected repo(s):

• cord-tester:
• https://gerrit.opencord.org/plugins/gitiles/cord-tester/+/refs/heads/master/requirements.txt
• voltha-system-tests
• https://gerrit.opencord.org/plugins/gitiles/voltha-system-tests/+/refs/heads/master/requirements.txt
• voltha-docs:
• https://gerrit.opencord.org/plugins/gitiles/voltha-docs/+/refs/heads/master/requirements.txt