ui: Update KaTeX package and clean up logs from sass warnings (#23275)

* ui: migrate katex imports to @use to resolve SCSS deprecation warnings

* ci: Use `ubuntu-slim` for CI (UI) workflow

tools/ui/src/styles/katex-custom.scss

@@ -8,6 +8,9 @@ $use-ttf: false;
 $font-folder: 'katex-fonts';
 
 // Import KaTeX SCSS with overridden variables
-// Note: @import is deprecated but required because KaTeX uses @import internally
-// The deprecation warnings are from KaTeX's code and cannot be avoided
-@import 'katex/src/styles/katex.scss';
+@use 'katex/src/styles/katex.scss' with (
+	$use-woff2: true,
+	$use-woff: false,
+	$use-ttf: false,
+	$font-folder: 'katex-fonts'
+);