[BEAM-13015] Disable retries for fnapi grpc channels which otherwise defaults on.

sdks/java/fn-execution/src/main/java/org/apache/beam/sdk/fn/channel/ManagedChannelFactory.java

@@ -89,6 +89,11 @@ public ManagedChannel forDescriptor(ApiServiceDescriptor apiServiceDescriptor) {
             // Set the message size to max value here. The actual size is governed by the
             // buffer size in the layers above.
             .maxInboundMessageSize(Integer.MAX_VALUE)
+            // Disable automatic retries as it introduces complexity and we send long-lived
+            // rpcs which will exceed the per-rpc retry request buffer and not be retried
+            // anyway. See
+            // https://github.com/grpc/proposal/blob/master/A6-client-retries.md#when-retries-are-valid
+            .disableRetry()
             .intercept(interceptors);
     if (directExecutor) {
       channelBuilder = channelBuilder.directExecutor();