[Ingest Manager] Set _meta in the index.mappings (#72026)

Co-authored-by: Elastic Machine <elasticmachine@users.noreply.github.com>

Author: afharo

x-pack/plugins/ingest_manager/server/services/epm/elasticsearch/template/__snapshots__/template.test.ts.snap

@@ -249,6 +249,15 @@ function getBaseTemplate(
   packageName: string,
   composedOfTemplates: string[]
 ): IndexTemplate {
+  // Meta information to identify Ingest Manager's managed templates and indices
+  const _meta = {
+    package: {
+      name: packageName,
+    },
+    managed_by: 'ingest-manager',
+    managed: true,
+  };
+
   return {
     // This takes precedence over all index templates installed by ES by default (logs-*-* and metrics-*-*)
     // if this number is lower than the ES value (which is 100) this template will never be applied when a data stream
@@ -304,19 +313,14 @@ function getBaseTemplate(
         date_detection: false,
         // All the properties we know from the fields.yml file
         properties: mappings.properties,
+        _meta,
       },
       // To be filled with the aliases that we need
       aliases: {},
     },
     data_stream: {},
     composed_of: composedOfTemplates,
-    _meta: {
-      package: {
-        name: packageName,
-      },
-      managed_by: 'ingest-manager',
-      managed: true,
-    },
+    _meta,
   };
 }