archiver: rename print_x methods so they correspond to log levels
archiver: rename print_x methods so they correspond to log levels

also:

remove some "Warning: " msg prefixes - if we emit at WARNING level,
it is obviously a warning.

remove some "borg: " msg prefixes.

edgewood/borg,edgimar/borg,mhubig/borg,mhubig/borg,edgimar/borg,raxenak/borg,edgimar/borg,raxenak/borg,raxenak/borg,RonnyPfannschmidt/borg,edgewood/borg,RonnyPfannschmidt/borg,raxenak/borg,edgewood/borg,RonnyPfannschmidt/borg,edgimar/borg,edgewood/borg,RonnyPfannschmidt/borg,mhubig/borg,RonnyPfannschmidt/borg