Remove cursor override for :disabled buttons (#14061)

Related to #8961 and
#8962

Before v4, buttons got this CSS in preflight:


https://github.com/tailwindlabs/tailwindcss/blob/9824cb64a03afaa405e184cb31003c8a1efafaa7/src/css/preflight.css#L339-L353

v4 (`next` branch) no longer has `cursor: pointer` in
[preflight.css](https://github.com/tailwindlabs/tailwindcss/blob/2fe249963583e436961adc59cf9988af454e3da5/packages/tailwindcss/preflight.css)

This PR removes additional CSS for `:disabled` buttons. It was meant to
undo an override that is no longer present.

Author: kachkaev

packages/@tailwindcss-postcss/src/__snapshots__/index.test.ts.snap

@@ -566,10 +566,6 @@ exports[`\`@import 'tailwindcss'\` is replaced with the generated CSS 1`] = `
     color: color-mix(in srgb, currentColor 50%, transparent);
   }
 
-  :disabled {
-    cursor: default;
-  }
-
   img, svg, video, canvas, audio, iframe, embed, object {
     vertical-align: middle;
     display: block;

packages/tailwindcss/preflight.css

@@ -289,14 +289,6 @@ textarea {
   color: color-mix(in srgb, currentColor 50%, transparent); /* 2 */
 }
 
-/*
-  Make sure disabled buttons don't get the pointer cursor.
-*/
-
-:disabled {
-  cursor: default;
-}
-
 /*
   1. Make replaced elements `display: block` by default. (https://github.com/mozdevs/cssremedy/issues/14)
   2. Add `vertical-align: middle` to align replaced elements more sensibly by default. (https://github.com/jensimmons/cssremedy/issues/14#issuecomment-634934210)