Remove S3 output stream (#27280)

Now the blob size information is available before writing anything,
the repository implementation can know upfront what will be the
more suitable API to upload the blob to S3.

This commit removes the DefaultS3OutputStream and S3OutputStream
classes and moves the implementation of the upload logic directly in the
S3BlobContainer.

related #26993
closes #26969

Author: tlrx

docs/plugins/repository-s3.asciidoc

@@ -206,9 +206,10 @@ The following settings are supported:
     http://docs.aws.amazon.com/AmazonS3/latest/dev/uploadobjusingmpu.html[AWS Multipart Upload API]
     to split the chunk into several parts, each of `buffer_size` length, and
     to upload each part in its own request. Note that setting a buffer
-    size lower than `5mb` is not allowed since it will prevents the use of the
-    Multipart API and may result in upload errors. Defaults to the minimum
-    between `100mb` and `5%` of the heap size.
+    size lower than `5mb` is not allowed since it will prevent the use of the
+    Multipart API and may result in upload errors. It is also not possible to
+    set a buffer size greater than `5gb` as it is the maximum upload size
+    allowed by S3. Defaults to the minimum between `100mb` and `5%` of the heap size.
 
 `max_retries`::