Convert legacy retryable reads tests to unified format

* Use "mapReduce" instead of "mapreduce" for the command name,
  as documented, and as expected by the tests.

JAVA-5344

Author: jyemin

driver-core/src/main/com/mongodb/internal/operation/MapReduceToCollectionOperation.java

@@ -300,7 +300,7 @@ private BsonDocument getCommand(@Nullable final ConnectionDescription descriptio
         if (getDatabaseName() != null) {
             outputDocument.put("db", new BsonString(getDatabaseName()));
         }
-        BsonDocument commandDocument = new BsonDocument("mapreduce", new BsonString(namespace.getCollectionName()))
+        BsonDocument commandDocument = new BsonDocument("mapReduce", new BsonString(namespace.getCollectionName()))
                                            .append("map", getMapFunction())
                                            .append("reduce", getReduceFunction())
                                            .append("out", outputDocument);

driver-core/src/main/com/mongodb/internal/operation/MapReduceWithInlineResultsOperation.java

@@ -231,7 +231,7 @@ private CommandCreator getCommandCreator(final SessionContext sessionContext) {
     }
 
     private BsonDocument getCommand(final SessionContext sessionContext, final int maxWireVersion) {
-        BsonDocument commandDocument = new BsonDocument("mapreduce", new BsonString(namespace.getCollectionName()))
+        BsonDocument commandDocument = new BsonDocument("mapReduce", new BsonString(namespace.getCollectionName()))
                                            .append("map", getMapFunction())
                                            .append("reduce", getReduceFunction())
                                            .append("out", new BsonDocument("inline", new BsonInt32(1)));

driver-core/src/test/functional/com/mongodb/internal/operation/MapReduceToCollectionOperationSpecification.groovy

@@ -247,7 +247,7 @@ class MapReduceToCollectionOperationSpecification extends OperationFunctionalSpe
 
         when:
         def operation =  new MapReduceToCollectionOperation(getNamespace(), mapF, reduceF, out, WriteConcern.MAJORITY)
-        def expectedCommand = new BsonDocument('mapreduce', new BsonString(getCollectionName()))
+        def expectedCommand = new BsonDocument('mapReduce', new BsonString(getCollectionName()))
                 .append('map', mapF)
                 .append('reduce', reduceF)
                 .append('out', BsonDocument.parse('{replace: "outCollection"}'))

driver-core/src/test/functional/com/mongodb/internal/operation/MapReduceWithInlineResultsOperationSpecification.groovy

@@ -155,7 +155,7 @@ class MapReduceWithInlineResultsOperationSpecification extends OperationFunction
         when:
         def operation = new MapReduceWithInlineResultsOperation<Document>(helper.namespace, new BsonJavaScript('function(){ }'),
                 new BsonJavaScript('function(key, values){ }'), bsonDocumentCodec)
-        def expectedCommand = new BsonDocument('mapreduce', new BsonString(helper.namespace.getCollectionName()))
+        def expectedCommand = new BsonDocument('mapReduce', new BsonString(helper.namespace.getCollectionName()))
             .append('map', operation.getMapFunction())
             .append('reduce', operation.getReduceFunction())
             .append('out', new BsonDocument('inline', new BsonInt32(1)))
@@ -235,7 +235,7 @@ class MapReduceWithInlineResultsOperationSpecification extends OperationFunction
         source.retain() >> source
         source.getServerApi() >> null
         def commandDocument = BsonDocument.parse('''
-            { "mapreduce" : "coll",
+            { "mapReduce" : "coll",
               "map" : { "$code" : "function(){ }" },
               "reduce" : { "$code" : "function(key, values){ }" },
               "out" : { "inline" : 1 },
@@ -284,7 +284,7 @@ class MapReduceWithInlineResultsOperationSpecification extends OperationFunction
         source.getConnection(_) >> { it[0].onResult(connection, null) }
         source.retain() >> source
         def commandDocument = BsonDocument.parse('''
-            { "mapreduce" : "coll",
+            { "mapReduce" : "coll",
               "map" : { "$code" : "function(){ }" },
               "reduce" : { "$code" : "function(key, values){ }" },
               "out" : { "inline" : 1 },