Add journald input support to filebeat

Journalbeat is removed in ELK 7.16 and merged into
filebeat. This patch adds defaults which allow this
input to be enabled via a single variable.

Depends-On: https://review.opendev.org/c/openstack/openstack-ansible-ops/+/843423
Change-Id: I5563d6493a6a53374170c4bdaa1edfbff85b300d

elk_metrics_7x/roles/elastic_filebeat/defaults/main.yml

@@ -282,6 +282,13 @@ filebeat_prospectors:
       - /var/log/elasticsearch/*.log
     tags:
       - beats
+  # Journald supported from filebeat >= 7.16.0
+  - type: journald
+    enabled: "{{ filebeat_journald_enabled | default(false) }}"
+    paths:
+      - /var/log/journal
+    tags:
+      - journal
 
 filebeat_ilm_policy_name: "filebeat-{{ beat_version }}"
 filebeat_ilm_policy_template: "filebeat-{{ beat_version }}"