Backport of do not set securityContext on Openshift < 4.11 (#2678)

[pglass]

Backport of #2678 to release/1.0.x

Changes proposed in this PR:

• This is going into release/1.1.x, and will be backported into release/1.0.x because both of those Consul K8s versions support K8s < 1.23.x and therefore support OpenShift <= 4.10
• Do not set securityContext on OpenShift < 4.11 because the restricted SCC disallows setting some of those settings. I broke this in Support running with restricted PSA enforcement enabled (part 1) #2572. In OpenShift >= 4.11, setting the securityContext is okay because the new restricted-v2 SCC is available to all users/accounts and allows setting the fields we want to set, and doing so avoids warnings.
• We determine the OpenShift version in Helm using the Kube version because there is a 1:1 mapping of OpenShift to Kube versions.

How I've tested this PR:

• Ran the connect tests with openshift enabled against 4.10 and 4.11 OpenShift clusters, using instructions similar to those in the description of Support running with restricted PSA enforcement enabled (part 1) #2572

How I expect reviewers to test this PR:

👀

[curtbushko]

LGTM!