Help center button too tall in IE11

[afercia]

In IE11 the Help Center button looks taller than in other browsers:

HelpCenterButton extends YoastButton which uses a CSS hack to fix an IE11 bug with min-height and flexbox.

https://github.com/Yoast/yoast-components/blob/214ee6f37fcb9bbc8fa9ce2ca5b5c5463c1894a1/composites/Plugin/Shared/components/YoastButton.js#L58-L65

So its min-height is hardcoded to 48 pixels because this value was the design requirement. If we want to change the min-height, then also the hack for IE11 needs to be adjusted accordingly.

[afercia]

See the branch 746-help-center-button-height-ie11