K8SPXC-1067: fix statefulset updates

[pooknull]

https://jira.percona.com/browse/K8SPXC-1067

The updatePod function missed some fields to update statefulsets and mostly contained duplicated code from pxc.Statefulset function.

This PR replaces duplicated code with pxc.Statefulset and also fixes K8SPXC-1061

[JNKPercona]

Test name	Status
affinity-8-0	passed
auto-tuning-8-0	passed
cross-site-8-0	passed
demand-backup-cloud-8-0	passed
demand-backup-encrypted-with-tls-8-0	passed
demand-backup-8-0	passed
haproxy-5-7	passed
haproxy-8-0	passed
init-deploy-5-7	passed
init-deploy-8-0	passed
limits-8-0	passed
monitoring-2-0-8-0	failure
one-pod-5-7	passed
one-pod-8-0	passed
pitr-8-0	passed
pitr-gap-errors-8-0	passed
proxy-protocol-8-0	passed
proxysql-sidecar-res-limits-8-0	passed
recreate-8-0	passed
restore-to-encrypted-cluster-8-0	passed
scaling-proxysql-8-0	passed
scaling-8-0	passed
scheduled-backup-5-7	failure
scheduled-backup-8-0	failure
security-context-8-0	passed
smart-update1-8-0	passed
smart-update2-8-0	passed
storage-8-0	passed
tls-issue-cert-manager-ref-8-0	passed
tls-issue-cert-manager-8-0	passed
tls-issue-self-8-0	passed
upgrade-consistency-8-0	passed
upgrade-haproxy-8-0	passed
upgrade-proxysql-8-0	passed
users-5-7	failure
users-8-0	failure
validation-hook-8-0	passed
We run 37 out of 37

commit: 942a556
image: perconalab/percona-xtradb-cluster-operator:PR-1277-942a5564