Remote 6.x transport BWC Layer for _shrink (#33236)

The shrink action was renamed to `_resize` with the addition
or split. This bwc layer is unnecessary on 7.x since 6.latest will
always use the resize action.

Author: s1monw

server/src/main/java/org/elasticsearch/action/ActionModule.java

@@ -131,9 +131,7 @@
 import org.elasticsearch.action.admin.indices.shards.IndicesShardStoresAction;
 import org.elasticsearch.action.admin.indices.shards.TransportIndicesShardStoresAction;
 import org.elasticsearch.action.admin.indices.shrink.ResizeAction;
-import org.elasticsearch.action.admin.indices.shrink.ShrinkAction;
 import org.elasticsearch.action.admin.indices.shrink.TransportResizeAction;
-import org.elasticsearch.action.admin.indices.shrink.TransportShrinkAction;
 import org.elasticsearch.action.admin.indices.stats.IndicesStatsAction;
 import org.elasticsearch.action.admin.indices.stats.TransportIndicesStatsAction;
 import org.elasticsearch.action.admin.indices.template.delete.DeleteIndexTemplateAction;
@@ -446,7 +444,6 @@ public <Request extends ActionRequest, Response extends ActionResponse> void reg
         actions.register(IndicesSegmentsAction.INSTANCE, TransportIndicesSegmentsAction.class);
         actions.register(IndicesShardStoresAction.INSTANCE, TransportIndicesShardStoresAction.class);
         actions.register(CreateIndexAction.INSTANCE, TransportCreateIndexAction.class);
-        actions.register(ShrinkAction.INSTANCE, TransportShrinkAction.class);
         actions.register(ResizeAction.INSTANCE, TransportResizeAction.class);
         actions.register(RolloverAction.INSTANCE, TransportRolloverAction.class);
         actions.register(DeleteIndexAction.INSTANCE, TransportDeleteIndexAction.class);