K8SPXC-1568: prevent having * prefix in proxyadmin password

[pooknull]

https://perconadev.atlassian.net/browse/K8SPXC-1568

DESCRIPTION

It's not possible to use a proxyadmin password, which starts with * char.

This PR ensures the operator generates proxyadmin password that do not begin with *.

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 all needed new/changed options added to the Helm Chart?
• 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?

[egegunes]

isn't rules ...string a bit confusing if we just passing usernames?

[pooknull]

7dd7f45

[JNKPercona]

Test Name	Result	Time
affinity-8-0	passed	00:06:14
auto-tuning-8-0	passed	00:19:34
backup-storage-tls-8-0	passed	00:22:05
cross-site-8-0	passed	00:34:10
custom-users-8-0	passed	00:12:26
demand-backup-cloud-8-0	passed	00:58:27
demand-backup-encrypted-with-tls-8-0	passed	00:44:39
demand-backup-8-0	passed	00:43:20
demand-backup-flow-control-8-0	passed	00:10:59
demand-backup-parallel-8-0	passed	00:08:44
demand-backup-without-passwords-8-0	passed	00:15:32
haproxy-5-7	passed	00:14:44
haproxy-8-0	passed	00:14:47
init-deploy-5-7	passed	00:17:17
init-deploy-8-0	passed	00:17:01
limits-8-0	passed	00:12:21
monitoring-2-0-8-0	passed	00:23:15
monitoring-pmm3-8-0	passed	00:18:07
one-pod-5-7	passed	00:14:30
one-pod-8-0	passed	00:14:38
pitr-8-0	passed	00:43:20
pitr-gap-errors-8-0	passed	00:57:50
proxy-protocol-8-0	passed	00:09:58
proxysql-sidecar-res-limits-8-0	passed	00:08:35
pvc-resize-5-7	passed	00:16:26
pvc-resize-8-0	passed	00:17:08
recreate-8-0	passed	00:17:36
restore-to-encrypted-cluster-8-0	failure	00:16:40
scaling-proxysql-8-0	passed	00:08:46
scaling-8-0	passed	00:11:22
scheduled-backup-5-7	passed	01:05:41
scheduled-backup-8-0	passed	01:04:38
security-context-8-0	passed	00:26:28
smart-update1-8-0	passed	00:36:55
smart-update2-8-0	passed	00:38:46
storage-8-0	passed	00:10:59
tls-issue-cert-manager-ref-8-0	passed	00:09:03
tls-issue-cert-manager-8-0	passed	00:11:28
tls-issue-self-8-0	passed	00:13:35
upgrade-consistency-8-0	passed	00:11:28
upgrade-haproxy-5-7	passed	00:24:29
upgrade-haproxy-8-0	passed	00:25:04
upgrade-proxysql-5-7	passed	00:14:07
upgrade-proxysql-8-0	passed	00:12:54
users-5-7	failure	00:18:01
users-8-0	passed	00:25:48
validation-hook-8-0	passed	00:01:57

Summary	Value
Tests Run	47/47
Job Duration	03:00:17
Total Test Time	17:22:13

commit: ae03d01
image: perconalab/percona-xtradb-cluster-operator:PR-2124-ae03d011