Revert "Update runners/spark/src/main/java/org/apache/beam/runners/spark/stateful/SparkGroupAlsoByWindowViaWindowSet.java"

This reverts commit 838cccd.

Author: tkaymak

runners/spark/src/main/java/org/apache/beam/runners/spark/stateful/SparkGroupAlsoByWindowViaWindowSet.java

@@ -524,7 +524,7 @@ JavaDStream<WindowedValue<KV<K, Iterable<InputT>>>> groupByKeyAndWindow(
             pairDStream.updateStateByKey(
                 // Raw cast to AbstractFunction1 suppresses Scala 2.12 (collection.Seq) vs
                 // Scala 2.13 (immutable.Seq) type difference — safe at runtime due to erasure.
-                (scala.Function2) updateFunc,
+                (scala.runtime.AbstractFunction1) updateFunc,
                 pairDStream.defaultPartitioner(pairDStream.defaultPartitioner$default$1()),
                 true,
                 JavaSparkContext$.MODULE$.fakeClassTag());