Master node count check conflates separate clusters deployed in same run

[Oddly]

Summary

In roles/elasticsearch/tasks/main.yml the task Count master nodes reads the
globally-accumulated Ansible group elasticsearch_role_master instead of
scoping to the hosts of the current play. When two Elasticsearch clusters (a
primary cluster and a separate monitoring cluster) are deployed from the same
ansible-playbook invocation — both running the same role — group_by appends
hosts from all plays to the same global group. The assertion that asserts an
odd master count then sees the sum across both clusters, not the count of the
current cluster.

Reproduction

1. Inventory with two cluster groups, e.g.:

   [elasticsearch]
   master-001
   master-002
   master-003
   
   [elasticsearch_mon]
   monitor-001   # single-node monitoring cluster, also master-eligible

2. Playbook that runs oddly.elasticstack.elasticsearch on both groups
   in the same run (separate plays).

3. Deploy passes the main cluster (3 masters, odd). During the monitor
   cluster play, group_by adds monitor-001 to the same
   elasticsearch_role_master group. Count master nodes now returns 4.

4. Check count of master nodes fails:

   There must be an odd count of master nodes. You have 4
   

Expected

Each cluster's master count is evaluated against the hosts in the current play
only. A 3-node main cluster passes (3 is odd). A 1-node monitor cluster also
passes (1 is odd).

Suggested fix

Scope the count to ansible_play_hosts_all (the hosts of the current play):

- name: Count master nodes
  ansible.builtin.set_fact:
-   elasticsearch_count_of_master_nodes: "{{ groups['elasticsearch_role_master'] | length }}"
+   elasticsearch_count_of_master_nodes: >-
+     {{ ansible_play_hosts_all | intersect(groups['elasticsearch_role_master'] | default([])) | length }}

Semantics: count the master-eligible nodes among the hosts of this play,
which is the cluster being deployed.

Environment

• Collection: oddly.elasticstack current main
• Ansible 2.19.x
• Two-cluster (main + monitoring) setup