HADOOP-19141. Vector IO: Update default values consistently (#6702)

Contributed by Dongjoon Hyun

hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/Constants.java

@@ -1423,12 +1423,12 @@ public final class Constants {
   /**
    * Default minimum seek in bytes during vectored reads : {@value}.
    */
-  public static final int DEFAULT_AWS_S3_VECTOR_READS_MIN_SEEK_SIZE = 4896; // 4K
+  public static final int DEFAULT_AWS_S3_VECTOR_READS_MIN_SEEK_SIZE = 4096; // 4K
 
   /**
    * Default maximum read size in bytes during vectored reads : {@value}.
    */
-  public static final int DEFAULT_AWS_S3_VECTOR_READS_MAX_MERGED_READ_SIZE = 1253376; //1M
+  public static final int DEFAULT_AWS_S3_VECTOR_READS_MAX_MERGED_READ_SIZE = 1048576; //1M
 
   /**
    * Maximum number of range reads a single input stream can have