DMI CSITs need to be aligned to CI-management/ CPS CSITs

Affected files:

csit/prepare-csit.sh

csit/run-csit.sh

csit/install-robotframework.sh

csit/pylibs.txt

Reference: 

132440: Fix: Update python environment to ROBOT3_VENV | https://gerrit.onap.org/r/c/cps/+/132440

132618: Chore: Re-instate robotframework-requests==0.9.3 | https://gerrit.onap.org/r/c/cps/+/132618

132773: Chore: Update robot-framework scripts to use Python3.10 | https://gerrit.onap.org/r/c/cps/+/132773

Extra:

132301: Fix: Swap run-csit.sh to Python3 robot framework | https://gerrit.onap.org/r/c/cps/+/132301

132306: Fix: Swap prepare-csit.sh to Python3 robot framework | https://gerrit.onap.org/r/c/cps/+/132306

132423: Fix: Call source_safely after function declaration | https://gerrit.onap.org/r/c/cps/+/132423