Update window using correct remaining() value (#4184)

This commit fixes an issue where the receive window for the CRT client is
updated with the value of remaining() *after* it's been read, which is incorrect
as this will be 0 if the buffer has been fully consumed, which is it should be.

services/s3/src/main/java/software/amazon/awssdk/services/s3/internal/crt/S3CrtResponseHandlerAdapter.java

@@ -69,6 +69,7 @@ public int onResponseBody(ByteBuffer bodyBytesIn, long objectRangeStart, long ob
             return 0;
         }
 
+        int bytesReceived = bodyBytesIn.remaining();
         CompletableFuture<Void> writeFuture = responsePublisher.send(bodyBytesIn);
 
         writeFuture.whenComplete((result, failure) -> {
@@ -77,7 +78,7 @@ public int onResponseBody(ByteBuffer bodyBytesIn, long objectRangeStart, long ob
                 return;
             }
 
-            metaRequest.incrementReadWindow(bodyBytesIn.remaining());
+            metaRequest.incrementReadWindow(bytesReceived);
         });
 
         // Returning 0 to disable flow control because we manually increase read window above