[SPARK-30267][SQL][FOLLOWUP] Use while loop in Avro Array Deserializer

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

This is a follow-up of #26907
It changes the for loop `for (element <- array.asScala)` to while loop

### Why are the changes needed?

As per https://github.com/databricks/scala-style-guide#traversal-and-zipwithindex, we should use while loop for the performance-sensitive code.

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

No

### How was this patch tested?

Existing tests.

Closes #27127 from gengliangwang/SPARK-30267-FollowUp.

Authored-by: Gengliang Wang <gengliang.wang@databricks.com>
Signed-off-by: Gengliang Wang <gengliang.wang@databricks.com>

Author: gengliangwang

external/avro/src/main/scala/org/apache/spark/sql/avro/AvroDeserializer.scala

@@ -167,13 +167,14 @@ class AvroDeserializer(rootAvroType: Schema, rootCatalystType: DataType) {
       case (ARRAY, ArrayType(elementType, containsNull)) =>
         val elementWriter = newWriter(avroType.getElementType, elementType, path)
         (updater, ordinal, value) =>
-          val array = value.asInstanceOf[java.util.Collection[Any]]
-          val len = array.size()
-          val result = createArrayData(elementType, len)
+          val collection = value.asInstanceOf[java.util.Collection[Any]]
+          val result = createArrayData(elementType, collection.size())
           val elementUpdater = new ArrayDataUpdater(result)
 
           var i = 0
-          for (element <- array.asScala) {
+          val iter = collection.iterator()
+          while (iter.hasNext) {
+            val element = iter.next()
             if (element == null) {
               if (!containsNull) {
                 throw new RuntimeException(s"Array value at path ${path.mkString(".")} is not " +