Issue 4611: Don't give RepeatTieColumn a `cause' event

Issue 4611: Don't give RepeatTieColumn a `cause' event

Rationale: the cause is used for point-and-click information and for
stuff like \parenthesize, and a RepeatTieColumn does not have metrics
that would be useful for that.  In particular, this causes code like

{ c'1-\parenthesize\repeatTie }

to compile without spurious parens and error messages.