UI upload creates temporary files in java.io.tmpdir

The UI upload creates temporary files in java.io.tmpdir that contain the uploaded content.  Presumably this content is then copied into blob storage.

This can lead to slow performance if java.io.tmpdir and blob storage are not on the same disk volume.

Expected:

The UI upload should upload to the temporary directory in the destination blob store so that a simple file rename can be used to move the temporary file into it's final destination.