[MINOR][CORE] Correct the number of started fetch requests in log

### What changes were proposed in this pull request?

When counting the number of started fetch requests, we should exclude the deferred requests.

### Why are the changes needed?

Fix the wrong number in the log.

### Does this PR introduce _any_ user-facing change?

Yes, users see the correct number of started requests in logs.

### How was this patch tested?

Manually tested.

Closes #32180 from Ngone51/count-deferred-request.

Lead-authored-by: yi.wu <[email protected]>
Co-authored-by: wuyi <[email protected]>
Signed-off-by: attilapiros <[email protected]>

core/src/main/scala/org/apache/spark/storage/ShuffleBlockFetcherIterator.scala

@@ -551,8 +551,10 @@ final class ShuffleBlockFetcherIterator(
     // Send out initial requests for blocks, up to our maxBytesInFlight
     fetchUpToMaxBytes()
 
-    val numFetches = remoteRequests.size - fetchRequests.size
-    logInfo(s"Started $numFetches remote fetches in ${Utils.getUsedTimeNs(startTimeNs)}")
+    val numDeferredRequest = deferredFetchRequests.values.map(_.size).sum
+    val numFetches = remoteRequests.size - fetchRequests.size - numDeferredRequest
+    logInfo(s"Started $numFetches remote fetches in ${Utils.getUsedTimeNs(startTimeNs)}" +
+      (if (numDeferredRequest > 0 ) s", deferred $numDeferredRequest requests" else ""))
 
     // Get Local Blocks
     fetchLocalBlocks()