Add torture_server_sftp_opendir_handles_exhaustion test that
exercises the error path in process_opendir() when all SFTP
handles are occupied. This covers the memory leak fix for
h->name that was missing in the sftp_handle_alloc() failure path.
The test exhausts all 256 handle slots with sftp_open(), then
verifies that sftp_opendir() fails gracefully without crashing
or leaking memory.
Signed-off-by: Mingyuan Li <2560359315@qq.com>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>