HADOOP-14138. Remove S3A ref from META-INF service discovery, rely on existing core-default entry.

Contributed by Steve Loughran

(cherry picked from commit 51fefbe38bf40373d2855163fa6444821b0f994c)

hadoop-tools/hadoop-aws/src/main/resources/META-INF/services/org.apache.hadoop.fs.FileSystem

@@ -14,4 +14,3 @@
 # limitations under the License.
 
 org.apache.hadoop.fs.s3native.NativeS3FileSystem
-org.apache.hadoop.fs.s3a.S3AFileSystem