fix: respect scan impl config for v2 scan (#3357)

Author: andygrove

spark/src/main/scala/org/apache/comet/rules/CometScanRule.scala

@@ -228,7 +228,7 @@ case class CometScanRule(session: SparkSession) extends Rule[SparkPlan] with Com
   private def transformV2Scan(scanExec: BatchScanExec): SparkPlan = {
 
     scanExec.scan match {
-      case scan: ParquetScan =>
+      case scan: ParquetScan if COMET_NATIVE_SCAN_IMPL.get() == SCAN_NATIVE_COMET =>
         val fallbackReasons = new ListBuffer[String]()
         val schemaSupported =
           CometBatchScanExec.isSchemaSupported(scan.readDataSchema, fallbackReasons)

spark/src/test/scala/org/apache/comet/exec/CometExecSuite.scala

@@ -382,9 +382,10 @@ class CometExecSuite extends CometTestBase {
     }
   }
 
-  test("ReusedExchangeExec should work on CometBroadcastExchangeExec") {
+  test("ReusedExchangeExec should work on CometBroadcastExchangeExec with V2 scan") {
     withSQLConf(
       CometConf.COMET_EXEC_BROADCAST_FORCE_ENABLED.key -> "true",
+      CometConf.COMET_NATIVE_SCAN_IMPL.key -> CometConf.SCAN_NATIVE_COMET,
       SQLConf.ADAPTIVE_EXECUTION_ENABLED.key -> "false",
       SQLConf.USE_V1_SOURCE_LIST.key -> "") {
       withTempPath { path =>

spark/src/test/scala/org/apache/comet/parquet/ParquetReadSuite.scala

@@ -2045,7 +2045,7 @@ class ParquetReadV2Suite extends ParquetReadSuite with AdaptiveSparkPlanHelper {
       case (cometEnabled, expectedScanner) =>
         testScanner(
           cometEnabled,
-          CometConf.SCAN_NATIVE_DATAFUSION,
+          CometConf.SCAN_NATIVE_COMET,
           scanner = expectedScanner,
           v1 = None)
     }

spark/src/test/scala/org/apache/comet/rules/CometScanRuleSuite.scala

@@ -101,11 +101,13 @@ class CometScanRuleSuite extends CometTestBase {
     }
   }
 
-  test("CometExecRule should replace BatchScanExec, but only when Comet is enabled") {
+  test("CometScanRule should replace V2 BatchScanExec, but only when Comet is enabled") {
     withTempPath { path =>
       createTestDataFrame.write.parquet(path.toString)
       withTempView("test_data") {
-        withSQLConf(SQLConf.USE_V1_SOURCE_LIST.key -> "") {
+        withSQLConf(
+          SQLConf.USE_V1_SOURCE_LIST.key -> "",
+          CometConf.COMET_NATIVE_SCAN_IMPL.key -> CometConf.SCAN_NATIVE_COMET) {
           spark.read.parquet(path.toString).createOrReplaceTempView("test_data")
 
           val sparkPlan =