fix: scalastyle errors - remove unused imports and unnecessary string interpolation

Author: Shekharrajak

spark/src/test/scala/org/apache/comet/CometIcebergCompactionBenchmarkTest.scala

@@ -222,7 +222,7 @@ class CometIcebergCompactionBenchmarkTest extends CometTestBase {
         val rowCount = spark.sql(s"SELECT COUNT(*) FROM $tableName").first().getLong(0)
 
         // scalastyle:off println
-        println(s"\n========== COMPACTION BENCHMARK ==========")
+        println("\n========== COMPACTION BENCHMARK ==========")
         println(s"Table: $tableName")
         println(s"Files before: $filesBefore, Rows: $rowCount")
         println("=" * 45)

spark/src/test/scala/org/apache/spark/sql/benchmark/CometIcebergTPCCompactionBenchmark.scala

@@ -19,16 +19,13 @@
 
 package org.apache.spark.sql.benchmark
 
-import java.io.{FileOutputStream, PrintStream}
 import java.io.File
 import java.util.Locale
 
 import org.apache.iceberg.spark.Spark3Util
 import org.apache.iceberg.spark.actions.SparkActions
 import org.apache.spark.sql.comet.CometNativeCompaction
 
-import org.apache.comet.CometConf
-
 /**
  * Benchmark to measure Iceberg compaction performance using TPC-H dataset. Compares Spark default
  * compaction (SparkBinPackDataRewriter) vs Comet-accelerated compaction
@@ -146,7 +143,7 @@ object CometIcebergTPCCompactionBenchmark extends CometBenchmarkBase {
       val nativeFilesAfter = spark.sql(s"SELECT * FROM $icebergTableName.files").count()
 
       // Write result
-      writeResult(s"lineitem_part", rowCount, fileCount, nativeFilesAfter, 0, nativeTimeMs, 0)
+      writeResult("lineitem_part", rowCount, fileCount, nativeFilesAfter, 0, nativeTimeMs, 0)
 
       spark.sql(s"DROP TABLE IF EXISTS $icebergTableName")
     }