CLOUD-808 Fix PMM server deployment in tests

[ptankov]

CHANGE DESCRIPTION

• In "functions" file create a function to deploy PMM server since we use it in at least two tests "monitoring" and "default-cr" and there's a possibility of having them different (actually bumped into this case).
• Combine IMAGE_PMM_SERVER_REPO and IMAGE_PMM_SERVER_TAG parameters in Jenkins pipelines into one IMAGE_PMM_SERVER (it's just excessive copy pasting, all the other images we have only one parameter for both)
• Rename IMAGE_PMM to IMAGE_PMM_CLIENT

CHECKLIST

Jira

• Is the Jira ticket created and referenced properly?
• Does the Jira ticket have the proper statuses for documentation (Needs Doc) and QA (Needs QA)?
• Does the Jira ticket link to the proper milestone (Fix Version field)?

Tests

• Is an E2E test/test case added for the new feature/change?
• Are unit tests added where appropriate?
• Are OpenShift compare files changed for E2E tests (compare/*-oc.yml)?

Config/Logging/Testability

• Are all needed new/changed options added to default YAML files?
• Are the manifests (crd/bundle) regenerated if needed?
• Did we add proper logging messages for operator actions?
• Did we ensure compatibility with the previous version or cluster upgrade process?
• Does the change support oldest and newest supported PXC version?
• Does the change support oldest and newest supported Kubernetes version?

[JNKPercona]

Test name	Status
affinity-8-0	passed
auto-tuning-8-0	passed
cross-site-8-0	failure
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	passed
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	passed
scheduled-backup-8-0	passed
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	passed
users-8-0	passed
validation-hook-8-0	passed
We run 37 out of 37

commit: 8a4f519
image: perconalab/percona-xtradb-cluster-operator:PR-1504-8a4f5192