Drop legacy font-face formats

After Microsoft ended support of IE8–10 back in January, we also did so on our currently maintained branches, i.e. 5.3 and 5.4 (see Certified Stack pages in docu).

Thus, the EOT format is obsolete for our various web fonts.
Additionally, TTF and SVG could go as well, as WOFF/WOFF2 have sufficient baselines of browser versions for us.
=> Going for the Practical Level of Browser Support from the CSS tricks article below.
Only mind if we use some semi-randomly generated query-param for the sake of icon font versions.

Useful links:

• https://css-tricks.com/snippets/css/using-font-face/
• https://creativemarket.com/blog/the-missing-guide-to-font-formats
• https://help.webflow.com/article/list-of-font-file-types-for-maximum-browser-support