Remove max channel count configurations to fall back to gax-grpc max channel count

Author: cindy-peng

google-cloud-datastore/src/main/java/com/google/cloud/datastore/DatastoreOptions.java

@@ -55,7 +55,6 @@ public class DatastoreOptions extends ServiceOptions<Datastore, DatastoreOptions
   public static final String LOCAL_HOST_ENV_VAR = "DATASTORE_EMULATOR_HOST";
   public static final int INIT_CHANNEL_COUNT = 1;
   public static final int MIN_CHANNEL_COUNT = 1;
-  public static final int MAX_CHANNEL_COUNT = 4;
 
   private transient TransportChannelProvider channelProvider = null;
 

google-cloud-datastore/src/main/java/com/google/cloud/datastore/spi/v1/GrpcDatastoreRpc.java

@@ -75,7 +75,7 @@ public GrpcDatastoreRpc(DatastoreOptions datastoreOptions) throws IOException {
               ? getClientContextForEmulator(datastoreOptions)
               : getClientContext(datastoreOptions);
 
-      /* For grpc transport options, configure default gRPC Connection pool with minChannelCount = 1 and maxChannelCount = 4 */
+      /* For grpc transport options, configure default gRPC Connection pool with minChannelCount = 1 */
       DatastoreStubSettings datastoreStubSettings =
           DatastoreStubSettings.newBuilder(clientContext)
               .applyToAllUnaryMethods(retrySettingSetter(datastoreOptions))
@@ -85,7 +85,6 @@ public GrpcDatastoreRpc(DatastoreOptions datastoreOptions) throws IOException {
                           ChannelPoolSettings.builder()
                               .setInitialChannelCount(DatastoreOptions.INIT_CHANNEL_COUNT)
                               .setMinChannelCount(DatastoreOptions.MIN_CHANNEL_COUNT)
-                              .setMaxChannelCount(DatastoreOptions.MAX_CHANNEL_COUNT)
                               .build())
                       .build())
               .build();