Add setup roles for passlib and pexpect for use with pause and vars_prompt tests (#43613)

* Add passlib to RHEL test instance

This looks like the only tests instance that is missing this libary. It is needed for vars_prompt tests.

* Create setup roles for pexect and passlib

Switch to using aliases rather than installing directly in the test scripts

test/integration/targets/pause/aliases

@@ -1 +1,2 @@
+setup/always/setup_pexpect
 shippable/posix/group3

test/integration/targets/pause/runme.sh

@@ -25,5 +25,4 @@ ansible-playbook pause-3.yml -i ../../inventory > /dev/null \
 ansible-playbook test-pause.yml -i ../../inventory "$@"
 
 # Interactively test pause
-pip install pexpect
 python test-pause.py -i ../../inventory "$@"