[etwist] remove no-longer-necessary uicache cleaning
It was done before we were actually up, which means it could be too
eager when combined with #6893185.
Closes #6893247.
import ConfigParser
try:
undo_actions = config.cfgfile_parser.get('MAIN', 'undo-support', False)
except ConfigParser.NoOptionError:
pass # this conf. file was probably already migrated
else:
config.global_set_option('undo-enabled', bool(undo_actions))