Fix e2e tests script failure on OpenShift
Fix e2e tests script failure on OpenShift

Set operator namespace in deployment validation as `openshift-operators`
when tests are run on openshift.

Signed-off-by: Nikhil Thomas <06117e966d039194d106149e879b10e553143831@redhat.com>

tektoncd/operator,tektoncd/operator,tektoncd/operator