Remove svg preload (#10654)

It triggers a warning in the Chrome console about it being unused, so I
think preloading of SVG assets may not be supported properly in current
browsers.

Co-authored-by: Lauris BH <lauris@nix.lv>
Co-authored-by: John Olheiser <john.olheiser@gmail.com>
Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: guillep2k <18600385+guillep2k@users.noreply.github.com>

templates/base/head.tmpl

@@ -103,7 +103,6 @@
 	<link rel="stylesheet" href="{{StaticUrlPrefix}}/vendor/assets/font-awesome/css/font-awesome.min.css">
 	<link rel="preload" as="font" href="{{StaticUrlPrefix}}/fomantic/themes/default/assets/fonts/icons.woff2" type="font/woff2" crossorigin="anonymous">
 	<link rel="preload" as="font" href="{{StaticUrlPrefix}}/fomantic/themes/default/assets/fonts/outline-icons.woff2" type="font/woff2" crossorigin="anonymous">
-	<link rel="preload" as="image" href="{{StaticUrlPrefix}}/img/svg/icons.svg">
 {{if .RequireSimpleMDE}}
 	<link rel="stylesheet" href="{{StaticUrlPrefix}}/vendor/plugins/simplemde/simplemde.min.css">
 {{end}}