[s3] Remove unnecessary getObjectMetadata() from getS3ObjectAndMetadata() (#1060)
[s3] Remove unnecessary getObjectMetadata() from getS3ObjectAndMetadata() (#1060)

* Remove unnecessary getObjectMetadata() from getS3ObjectAndMetadata()

ObjectMetadata is available from S3Object.getObjectMetadata().
We don't need to send a separate GetObjectMetadata Request (an
HTTP HEAD request), in order to get the metadata. This will double
performance for read workloads.

Signed-off-by: Xing Lin <Xing.Lin@netapp.com>

* Remove one unused import to pass style check.

Signed-off-by: Xing Lin <08f01e94e04669282427493609677b75cb68a829@netapp.com>
(cherry picked from commit 381aaebc83476e1d1c844f6db207f336bea4f8c6)

brianfrankcooper/YCSB,ChristianNavolskyi/YCSB,brianfrankcooper/YCSB,leschekhomann/YCSB,ChristianNavolskyi/YCSB,leschekhomann/YCSB,brianfrankcooper/YCSB,ChristianNavolskyi/YCSB,leschekhomann/YCSB,brianfrankcooper/YCSB,leschekhomann/YCSB,ChristianNavolskyi/YCSB