Remove the unused executor builder for vector tile plugin (#96577)

It is a left over from the original development of this end point and not used anywhere.

Author: iverase

docs/changelog/96577.yaml

@@ -0,0 +1,15 @@
+pr: 96577
+summary: Remove the unused executor builder for vector tile plugin
+area: Geo
+type: breaking
+issues: []
+breaking:
+  title: Remove the unused executor builder for vector tile plugin
+  area: Cluster and node setting
+  details: "The threadpool called `vectortile` is a left over from the original development of the\
+    \ vector tile search end point and it is used nowhere. It can still be a breaking change\
+    \ if it is configured on the elasticsearch yml file, for example by changing the threadpool\
+    \ size `thread_pool.vectortile.size=8`'"
+  impact: "In the case the threadpool appears on the yaml file, Elasticsearch will not start until those\
+    \ lines are removed."
+  notable: false

x-pack/plugin/vector-tile/src/main/java/org/elasticsearch/xpack/vectortile/VectorTilePlugin.java

@@ -17,12 +17,9 @@
 import org.elasticsearch.plugins.Plugin;
 import org.elasticsearch.rest.RestController;
 import org.elasticsearch.rest.RestHandler;
-import org.elasticsearch.threadpool.ExecutorBuilder;
-import org.elasticsearch.threadpool.FixedExecutorBuilder;
 import org.elasticsearch.xpack.core.XPackPlugin;
 import org.elasticsearch.xpack.vectortile.rest.RestVectorTileAction;
 
-import java.util.Collections;
 import java.util.List;
 import java.util.function.Supplier;
 
@@ -45,17 +42,4 @@ public List<RestHandler> getRestHandlers(
     ) {
         return List.of(new RestVectorTileAction());
     }
-
-    @Override
-    public List<ExecutorBuilder<?>> getExecutorBuilders(Settings settings) {
-        FixedExecutorBuilder indexing = new FixedExecutorBuilder(
-            settings,
-            "vector_tile_generation",
-            1,
-            -1,
-            "thread_pool.vectortile",
-            false
-        );
-        return Collections.singletonList(indexing);
-    }
 }