Removed references to simplified query format from error messages

Author: Mikep86

x-pack/plugin/rank-rrf/src/main/java/org/elasticsearch/xpack/rank/linear/LinearRetrieverBuilder.java

@@ -292,11 +292,11 @@ protected RetrieverBuilder doRewrite(QueryRewriteContext ctx) {
             var localIndicesMetadata = resolvedIndices.getConcreteLocalIndicesMetadata();
             if (localIndicesMetadata.size() > 1) {
                 throw new IllegalArgumentException(
-                    "[" + NAME + "] does not support the simplified query format when querying multiple indices"
+                    "[" + NAME + "] cannot specify [" + QUERY_FIELD.getPreferredName() + "] when querying multiple indices"
                 );
             } else if (resolvedIndices.getRemoteClusterIndices().isEmpty() == false) {
                 throw new IllegalArgumentException(
-                    "[" + NAME + "] does not support the simplified query format when querying remote indices"
+                    "[" + NAME + "] cannot specify [" + QUERY_FIELD.getPreferredName() + "] when querying remote indices"
                 );
             }
 

x-pack/plugin/rank-rrf/src/test/java/org/elasticsearch/xpack/rank/linear/LinearRetrieverBuilderTests.java

@@ -191,7 +191,7 @@ public void testSearchRemoteIndex() {
         );
 
         IllegalArgumentException iae = expectThrows(IllegalArgumentException.class, () -> retriever.doRewrite(queryRewriteContext));
-        assertEquals("[linear] does not support the simplified query format when querying remote indices", iae.getMessage());
+        assertEquals("[linear] cannot specify [query] when querying remote indices", iae.getMessage());
     }
 
     private static ResolvedIndices createMockResolvedIndices(

x-pack/plugin/rank-rrf/src/yamlRestTest/resources/rest-api-spec/test/linear/20_linear_retriever_simplified.yml

@@ -350,7 +350,7 @@ setup:
               query: "match"
               normalizer: "minmax"
 
-  - match: { error.root_cause.0.reason: "[linear] does not support the simplified query format when querying multiple indices" }
+  - match: { error.root_cause.0.reason: "[linear] cannot specify [query] when querying multiple indices" }
 
   - do:
       indices.put_alias:
@@ -371,7 +371,7 @@ setup:
               query: "match"
               normalizer: "minmax"
 
-  - match: { error.root_cause.0.reason: "[linear] does not support the simplified query format when querying multiple indices" }
+  - match: { error.root_cause.0.reason: "[linear] cannot specify [query] when querying multiple indices" }
 
 ---
 "Wildcard field patterns that do not resolve to any field are handled gracefully":