remove unused import

Author: wangshisan

sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/InMemoryFileIndex.scala

@@ -31,7 +31,6 @@ import org.apache.spark.internal.Logging
 import org.apache.spark.metrics.source.HiveCatalogMetrics
 import org.apache.spark.sql.SparkSession
 import org.apache.spark.sql.execution.streaming.FileStreamSink
-import org.apache.spark.sql.internal.SQLConf
 import org.apache.spark.sql.types.StructType
 import org.apache.spark.util.SerializableConfiguration