sftp output does not retry after a failed transfer operation. (Connection failed)

Version 4.61.0:

It seems that when there is an issue with the sftp, say a permissions issue on overwriting a file, the sftp output will never reconnect to the sftp server. First there is a permission denied issue overwriting a file on the remote:

time="2025-08-12T17:45:56Z" level=error msg="Failed to send message to sftp: failed to open remote file: permission denied" @service=redpanda-connect label="" path=root.output.broker.outputs.0 stream=sftp

Then after the failure I start seeing these messages in the log:

time="2025-08-12T17:45:57Z" level=error msg="Failed to send message to sftp: failed to create SFTP client: ssh: rejected: connect failed (open failed)" @service=redpanda-connect label="" path=root.output.broker.outputs.0 stream=sftp

And on and on forever until this morning:

time="2025-08-13T16:21:14Z" level=error msg="Failed to send message to sftp: failed to create SFTP client: ssh: rejected: connect failed (open failed)" @service=redpanda-connect label="" path=root.output.broker.outputs.0 stream=sftp

If I restart my redpanda-connect pod, transfers resume normally. I believe this is a bug with the reuse of the ssh connection in the sftp output.

Start by locating the SFTP output implementation and tracing how it reuses the SSH connection after a failed remote file operation. Reproduce the permission-denied transfer failure, then verify that the output reconnects and resumes transfers without restarting the redpanda-connect pod.