K8SPSMDB-1146 clarify incode the purpose of the databaseAdmin user

[gkech]

CHANGE DESCRIPTION

Problem:
Not a problem, clarify with a comment the purpose of the databaseAdmin user in our codebase and why it exists since it is not used by the operator.

Cause:
Short explanation of the root cause of the issue if applicable.

Solution:
Short explanation of the solution we are providing with this PR.

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 MongoDB version?
• Does the change support oldest and newest supported Kubernetes version?

[JNKPercona]

Test name	Status
arbiter	failure
balancer	failure
cross-site-sharded	failure
custom-replset-name	failure
custom-tls	failure
custom-users-roles	failure
custom-users-roles-sharded	failure
data-at-rest-encryption	failure
data-sharded	failure
demand-backup	failure
demand-backup-eks-credentials-irsa	skipped
demand-backup-fs	skipped
demand-backup-if-unhealthy	skipped
demand-backup-incremental	skipped
demand-backup-incremental-sharded	skipped
demand-backup-physical-parallel	skipped
demand-backup-physical-aws	skipped
demand-backup-physical-azure	skipped
demand-backup-physical-gcp-s3	skipped
demand-backup-physical-gcp-native	skipped
demand-backup-physical-minio	skipped
demand-backup-physical-sharded-parallel	skipped
demand-backup-physical-sharded-aws	skipped
demand-backup-physical-sharded-azure	skipped
demand-backup-physical-sharded-gcp-native	skipped
demand-backup-physical-sharded-minio	skipped
demand-backup-sharded	skipped
expose-sharded	skipped
finalizer	skipped
ignore-labels-annotations	skipped
init-deploy	skipped
ldap	skipped
ldap-tls	skipped
limits	skipped
liveness	skipped
mongod-major-upgrade	skipped
mongod-major-upgrade-sharded	skipped
monitoring-2-0	skipped
monitoring-pmm3	skipped
multi-cluster-service	skipped
multi-storage	skipped
non-voting-and-hidden	skipped
one-pod	skipped
operator-self-healing-chaos	skipped
pitr	skipped
pitr-physical	skipped
pitr-sharded	skipped
pitr-to-new-cluster	skipped
pitr-physical-backup-source	skipped
preinit-updates	skipped
pvc-resize	skipped
recover-no-primary	skipped
replset-overrides	skipped
rs-shard-migration	skipped
scaling	skipped
scheduled-backup	skipped
security-context	skipped
self-healing-chaos	skipped
service-per-pod	skipped
serviceless-external-nodes	skipped
smart-update	skipped
split-horizon	skipped
stable-resource-version	skipped
storage	skipped
tls-issue-cert-manager	skipped
upgrade	skipped
upgrade-consistency	skipped
upgrade-consistency-sharded-tls	skipped
upgrade-sharded	skipped
upgrade-partial-backup	skipped
users	skipped
version-service	skipped
We run 10 out of 72

commit: ce6d25e
image: perconalab/percona-server-mongodb-operator:PR-2089-ce6d25ed

[egegunes]

while documenting this, let's add some descriptive comments to other users as well