Network requirements to be installed by ansible-test (#40042)

Previously the test framework (DCI, Zuul) were installing the various
dependencies, this meant the list of what was required was duplicated.

Having everything defined in ansible-test makes it easier for people to
run tests locally.

Also this allows the test to work correctly on Python 2 & Python 3

test/runner/requirements/network-integration.txt

@@ -3,3 +3,6 @@ jinja2
 junit-xml
 paramiko
 pyyaml
+pexpect # for _user test
+ncclient # for Junos
+jxmlease # for Junos