Internal: remove bwc leftover

This caused some test failures as the readFrom method was not in sync anymore with the writeTo

Author: javanna

src/main/java/org/elasticsearch/action/search/SearchRequest.java

@@ -21,7 +21,6 @@
 
 import org.elasticsearch.ElasticsearchGenerationException;
 import org.elasticsearch.ElasticsearchIllegalArgumentException;
-import org.elasticsearch.Version;
 import org.elasticsearch.action.ActionRequest;
 import org.elasticsearch.action.ActionRequestValidationException;
 import org.elasticsearch.action.IndicesRequest;
@@ -545,9 +544,6 @@ public Boolean queryCache() {
     @Override
     public void readFrom(StreamInput in) throws IOException {
         super.readFrom(in);
-        if (in.getVersion().before(Version.V_1_2_0)) {
-            in.readByte(); // backward comp. for operation threading
-        }
         searchType = SearchType.fromId(in.readByte());
 
         indices = new String[in.readVInt()];