logger: remote: use lazy formatting
logger: remote: use lazy formatting

Part of #1843

As our previous investigations showed, path stringification and stuff
like relpath are taking a very large chunk of time when working with
giant directories. This patch removes `format()`s and uses lazy
formatting provided by logger instead, so stuff like path_info is not
stringified until actually needed (e.g. on `-v`).

dmpetrov/dataversioncontrol,efiop/dvc,efiop/dvc,dmpetrov/dataversioncontrol