Writing into sstable component output stream should be done with care.
In particular -- flushing can happen only once right before closing the
stream. Flushing the stream in between several writes is not going to
work, because file stream would step on unaligned IO and S3 upload
stream would send completion message to the server and would lose any
subsequent write.
Having said that, it's better to remove the flush() ability from the
component writer not to tempt the developers.
refs: #13320
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
886a1392a8