resolve [#33374] Extrude and mirror editing

mirror editing option was only added to extrude so mirror editing would always be disabled.
the option is now hidden to avoid confusing users.


git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@57494 954f8c5b-7b00-dc11-b283-0030488c597c