Remove non-obvious conf settings from TPCDS benchmark

## What changes were proposed in this pull request?

My fault -- these 2 conf entries are mysteriously hidden inside the benchmark code and makes it non-obvious to disable whole stage codegen and/or the vectorized parquet reader.

PS: Didn't attach a JIRA as this change should otherwise be a no-op (both these conf are enabled by default in Spark)

## How was this patch tested?

N/A

Author: Sameer Agarwal <sameer@databricks.com>

Closes #13726 from sameeragarwal/tpcds-conf.

sql/core/src/test/scala/org/apache/spark/sql/execution/benchmark/TPCDSQueryBenchmark.scala

@@ -64,8 +64,6 @@ object TPCDSQueryBenchmark {
     require(dataLocation.nonEmpty,
       "please modify the value of dataLocation to point to your local TPCDS data")
     val tableSizes = setupTables(dataLocation)
-    spark.conf.set(SQLConf.PARQUET_VECTORIZED_READER_ENABLED.key, "true")
-    spark.conf.set(SQLConf.WHOLESTAGE_CODEGEN_ENABLED.key, "true")
     queries.foreach { name =>
       val queryString = fileToString(new File(Thread.currentThread().getContextClassLoader
         .getResource(s"tpcds/$name.sql").getFile))