Remove extra whitespace in pg_upgrade status message.
There's no need to add another level of indentation to this status
message. pg_log() will put it in the right place.
Oversight in commit
347758b120.
Reviewed-by: Daniel Gustafsson
Discussion: https://postgr.es/m/ZunW7XHLd2uTts4f%40nathan
Backpatch-through: 17