journald: Use 'match' field for include_matches

The `include_matches` configuration for journald inputs was updated in Filebeat 8.16.
This change migrates the configuration to the new schema where array values are now expected under the YAML object `include_matches.match`.

Reference:
- https://www.elastic.co/guide/en/beats/libbeat/8.16/release-notes-8.16.0.html
- https://www.elastic.co/guide/en/beats/filebeat/8.16/filebeat-input-journald.html#filebeat-input-journald-include-matches

Author: trauta

templates/input.yml.erb

@@ -54,8 +54,9 @@
     <%- end -%>
     <%- if @include_matches.length > 0 -%>
   include_matches:
+    match:
       <%- @include_matches.each do |match| -%>
-    - <%= match %>
+      - <%= match %>
       <%- end -%>
     <%- end -%>
   <%- else -%>