HDDS-13828. Verify number of replicas for om and scm

[shuan1026]

What changes were proposed in this pull request?

• Adds a Replicas section to NOTES.txt so helm install / upgrade prints the configured om.replicas and scm.replicas.
• Emits a WARNING when either count is even (Raft quorum is better with odd sizes), but does not fail the install.
• Even replica counts remain allowed for OM/SCM migration intermediate states (see Jira discussion and RATIS-2296). Odd counts such as 5 are valid and are not warned.

What is the link to the Apache JIRA

https://issues.apache.org/jira/browse/HDDS-13828

How was this patch tested?

• Green CI run
• Manual verification:

# NOTES are not shown by default with helm template; use dry-run
helm install ozone charts/ozone --dry-run --debug 2>&1 | tee /tmp/notes-default.txt
grep -nE 'Replicas|om.replicas|scm.replicas|WARNING' /tmp/notes-default.txt

# Even counts should show WARNING
helm install ozone charts/ozone --dry-run --set om.replicas=2 --set scm.replicas=4 2>&1 \
  | grep -E 'WARNING|om.replicas|scm.replicas'

# Odd non-1/3 (e.g. 5) must not fail / must not warn as even
helm install ozone charts/ozone --dry-run --set om.replicas=5 --set scm.replicas=1 2>&1 \
  | grep -E 'WARNING|om\.replicas\)|fail|Replicas'

[adoroszlai]

@dnskr please review if you have time

[dnskr]

The templating looks good and the changes address the issue discussion.

I left two minor comments, and once those are handled, could you also add RATIS-2296 link into the PR description?

[shuan1026]

Thanks for the review, @dnskr! Both suggestions have been applied:

• Fixed the NOTES.txt header alignment
• Removed the redundant int cast, using .Values.om.replicas / .Values.scm.replicas directly
• Also, the RATIS-2296 link is add into the PR description.

[chungen0126]

+1 LGTM