cmdutil: remove unused 'confirmopts' constant

Follows up f10cb49951e1.

mercurial/cmdutil.py

@@ -63,11 +63,6 b' dryrunopts = ['
      _('do not perform actions, just print output')),
 ]
 
-confirmopts = [
-    ('', 'confirm', None,
-     _('ask before applying actions')),
-]
-
 remoteopts = [
     ('e', 'ssh', '',
      _('specify ssh command to use'), _('CMD')),