Do not install CrossPlane when using OpenShift

[gyliu513]

What steps did you take and what happened: [A clear and concise description on how to REPRODUCE the bug.]

What did you expect to happen:

We should leverage the openshift operator hub to install crossplane.

We need to update the document to highlight this.

@cloud-pak-gitops/cp4wiops-gitops-core

Anything else you would like to add: [Miscellaneous information that will assist in solving the issue.]

Environment:

• Minikube/KIND version:
• Kubernetes version: (use kubectl version):
• OS (e.g. from /etc/os-release):
• Instana version:
• Crossplane version:

[gyliu513]

we are not going to use Crossplane for latest Instana install.