Fix empty log message in AuronUniffleShuffleReader

[slfan1989]

Problem

In AuronUniffleShuffleReader.scala, there is an empty log statement that provides no useful information when empty shuffle partitions are detected:

if (!emptyPartitionIds.isEmpty) {
  logInfo(s"")  // Empty log message
}

This makes debugging and monitoring difficult as we cannot identify which partitions are empty during shuffle operations.

Solution

Replace the empty log message with meaningful information that includes:
The count of empty shuffle partitions
The list of empty partition IDs:

if (!emptyPartitionIds.isEmpty) {
  logInfo(s"Found ${emptyPartitionIds.size()} empty shuffle partitions: ${emptyPartitionIds.asScala.mkString(",")}")
}