Reduce amount of scroll listeners in the header

[alizedebray]

          Because if the scrollParent is the <html/> element, the this.scrollParent listener is not working and vice versa.

Binding both listeners, ensures, we can always call this.handleScrollEvent, no matter which element is the scroll parent. And the other listener will just not being called.

Originally posted by @oliverschuerch in #4786 (comment)

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The headers is currently adding listeners to both its scroll parent and the window, check if we can set one or the other instead of both