Improve font-size/data glyph balance

[markov00]

From elastic/eui#4845 (comment):

Our bar charts, and charts in general are configured with a suboptimal balance of font size and data glyph (bar rectangle, etc.) shape. The fonts are small and the data shapes are large. It looks like a functional prototype not the final product. It's also an issue from an accessibility viewpoint: the user gets a huge piece of help in determining the screenspace size of the data shapes, but it's at the expense of font size. Also, even if there's ample room and the user has something like 3 bars, it shouldn't take up all that space. There ought to be a ratio of font size to bar width. For example, on the above images, the bar thickness is easily 3x that of the category labels, and the slightly taller value label inside the bar is also barely over 1/3rd of the height. 1.618x (golden ratio) to around 2x ratio would work but 3x is visually and accessibility wise unbalanced. Eg. this uses around 2x, despite few bars (if there are many bars, it's OK for the text to be about as tall as the bar is thick). This page has a couple of bad examples or unsupported advice, but most charts have a good font/shape balance. Big bars, small fonts is the main way to recognize Kibana visualizations in the wild