Cleanup redundant InstanceShardOperationRequest

As stated by the TODO, this thing can just be inlined into the update
request which I have done here.

Author: original-brownbear

server/src/main/java/module-info.java

@@ -149,7 +149,6 @@
     exports org.elasticsearch.action.support.master.info;
     exports org.elasticsearch.action.support.nodes;
     exports org.elasticsearch.action.support.replication;
-    exports org.elasticsearch.action.support.single.instance;
     exports org.elasticsearch.action.support.single.shard;
     exports org.elasticsearch.action.support.tasks;
     exports org.elasticsearch.action.termvectors;