Updates Labor Roundtable reg form for Worker Institute changes

Updates Labor Roundtable reg form to match changes done in CommonSpot when this form moved to Worker Institute:  (1) remove Major and How Did You Hear About LR fields (2) switch to new admin email.
NOTE - the two fields that were removed from this form need to be deleted from field bases; see the "Delete unused field bases" story in Tracker.  The fields are field_major and field_referral_textarea.