Openshift support

[ishustava]

Changes proposed in this PR

Helm chart values and template changes

• Add a new Helm value global.openshift.enabled
• Add a SecurityContextConstraint for the consul clients when global.openshift.enabled is set to true
• Don't set fsGroup for the servers when global.openshift.enabled is set to true
• Remove server.disableFsGroupSecurityContext value and fail in the chart if someone tries to set it
• Increase memory limits and requests from 25Mi to 50Mi for all jobs and service-init containers in the terminating and ingress gateway deployments. This was mostly determined by running the tests. There are other containers that still have the 25Mi memory request and limit, however those containers were not causing failures on OpenShift.

Acceptance tests changes

• Add a new flag -enable-openshift to the framework which will set global.openshift.enabled to true for all helm installs/upgrades.
• Increase timeouts in various places because it takes longer for things to be created on OpenShift.
• Change consul-dns test to retry and to not use TTY since it's not always available.

CI changes

• Add a new job to run acceptance tests against OpenShift. Note that it currently runs against pre-created Azure Red Hat OpenShift clusters. I was not able to get terraform running to create them before each run due to a variety of reasons, the main one being that it takes a not yet determined amount of time for the clusters to become ready. It has been hard to determine that time in a script/CI, which resulted in intermittent/non-deterministic test failures. We will have to address further automation of the OpenShift cluster creation at a later time.
• Add a new workflow to run acceptance tests nightly (currently commented out).
• Add Azure CLI and OpenShift CLI to the Docker image used in CI

[lkysow]

🎉 🦊 Looks simple enough 😆

[kschoche]

Great work @ishustava!!
One quick question about the comments in values.yaml :
Does it make sense to add a comment saying
"this has been tested on openshift version X?"
so that users have an idea of what a supportable version would be?

[ishustava]

Does it make sense to add a comment saying
"this has been tested on openshift version X?"

yeah! I think that's a great idea!