Adding aggregations support for the _ignored field

docs/reference/search/profile.asciidoc

@@ -194,7 +194,7 @@ The API returns the following result:
             "load_source_count": 5
           },
           "debug": {
-            "stored_fields": ["_id", "_ignored", "_routing", "_source"]
+            "stored_fields": ["_id", "_routing", "_source"]
           },
           "children": [
             {
@@ -1051,7 +1051,7 @@ And here is the fetch profile:
             "load_source_count": 5
           },
           "debug": {
-            "stored_fields": ["_id", "_ignored", "_routing", "_source"]
+            "stored_fields": ["_id", "_routing", "_source"]
           },
           "children": [
             {

rest-api-spec/src/yamlRestTest/resources/rest-api-spec/test/get/120_stored_fields_ignored.yml

@@ -1,9 +1,8 @@
 ---
 "_ignored field through get api using stored_fields":
   - skip:
-      #TODO(101373): this will actually be introduced in 8.15 so change this skip version accordingly after we branch
-      reason: "_ignored metadata field uses doc values instead of stored field from version 8.14"
-      version: " - 8.13.99"
+      reason: "_ignored metadata field uses doc values instead of stored field from version 8.15"
+      version: " - 8.14.99"
   - do:
       indices.create:
         index: test

rest-api-spec/src/yamlRestTest/resources/rest-api-spec/test/search/370_profile.yml

@@ -41,7 +41,7 @@ fetch fields:
   - gt: { profile.shards.0.fetch.breakdown.next_reader: 0 }
   - gt: { profile.shards.0.fetch.breakdown.load_stored_fields_count: 0 }
   - gt: { profile.shards.0.fetch.breakdown.load_stored_fields: 0 }
-  - match: { profile.shards.0.fetch.debug.stored_fields: [_id, _ignored, _routing, _source] }
+  - match: { profile.shards.0.fetch.debug.stored_fields: [_id, _routing, _source] }
   - length: { profile.shards.0.fetch.children: 2 }
   - match: { profile.shards.0.fetch.children.0.type: FetchFieldsPhase }
   - gt: { profile.shards.0.fetch.children.0.breakdown.next_reader_count: 0 }
@@ -74,7 +74,7 @@ fetch source:
   - gt: { profile.shards.0.fetch.breakdown.next_reader: 0 }
   - gt: { profile.shards.0.fetch.breakdown.load_stored_fields_count: 0 }
   - gt: { profile.shards.0.fetch.breakdown.load_stored_fields: 0 }
-  - match: { profile.shards.0.fetch.debug.stored_fields: [_id, _ignored, _routing, _source] }
+  - match: { profile.shards.0.fetch.debug.stored_fields: [_id, _routing, _source] }
   - length: { profile.shards.0.fetch.children: 3 }
   - match: { profile.shards.0.fetch.children.0.type: FetchFieldsPhase }
   - match: { profile.shards.0.fetch.children.1.type: FetchSourcePhase }
@@ -160,7 +160,6 @@ disabling stored fields removes fetch sub phases:
       version: ' - 7.15.99'
       reason: fetch profiling implemented in 7.16.0
 
-
   - do:
       search:
         index: test

server/src/main/java/org/elasticsearch/index/mapper/IgnoredFieldMapper.java

@@ -15,7 +15,6 @@
 import org.apache.lucene.search.Query;
 import org.apache.lucene.search.TermRangeQuery;
 import org.apache.lucene.util.BytesRef;
-import org.elasticsearch.Version;
 import org.elasticsearch.index.IndexVersion;
 import org.elasticsearch.index.IndexVersions;
 import org.elasticsearch.index.fielddata.FieldData;
@@ -77,17 +76,6 @@ public Query existsQuery(SearchExecutionContext context) {
             // field is bounded by the number of fields in the mappings.
             return new TermRangeQuery(name(), null, null, true, true);
         }
-
-        @Override
-        public IndexFieldData.Builder fielddataBuilder(FieldDataContext fieldDataContext) {
-            throw new IllegalArgumentException(
-                "aggregations on the '"
-                    + typeName()
-                    + "' field are supported for indices created by version "
-                    + Version.V_8_15_0
-                    + " or higher"
-            );
-        }
     }
 
     public static final class IgnoredFieldType extends StringFieldType {