Check that OpenShift podPidsLimit / pidsLimit is not default 1024

As per https://access.redhat.com/solutions/5366631, OpenShift by default only allows 1024 processes (also threads) to be created - see https://access.redhat.com/solutions/5366631

This can cause significant problems for Couchbase Server as it typically needs more threads than that (say on a 16 core machine) - see linked CBSEs.

As I understand it, the Operator cannot directly check the limit; however I believe that the limit is exposed inside the container via /sys - specifically /sys/fs/cgroup/pids/pids.max:

Request is to check the value of this, and fail certification if the value is less than some more sensible number - 10,000 seems reasonable given that's what we currently check for the nproc ulimit:

[Thu 21 Oct 16:20:58 BST 2021] simon@symphony ~/src/github.com/couchbase/couchbase-operator/dist/couchbase-autonomous-operator-kubernetes_2.3.0-beta1-linux-x86_64 bin/cao certify --image couchbase/operator-certification:2.3.0-beta1 -- -server-image couchbase/server:7.0.2 -test TestCreateCluster

Initializing ...

Creating service account ...

Creating cluster role ...

Creating cluster role binding ...

Creating artifacts volume ...

Creating pull secrets ...

Creating certification pod ...

Waiting for certification pod to become ready ...

Certification pod running, streaming logs ...

couchbase-operator-certification 2.3.0 (build 999)

INFO[0000] Platform Preflight Checks            

INFO[0000] Number of processes = unlimited (>= 10000) ✔ 

INFO[0000] Number of open files = 1048576 (>= 70000) ✔ 

NOTE: I don't have an OpenShift environment to hand, so I cannot be sure if /sys/fs/cgroup/pids/pids.max is the correct path (or even exists there) - that does exist under Docker, and is a reasonable sibling path to the /sys/fs/cgroup/pids/pids.current path mentioned in the aforementioned RH Knowledgebase article.