Fix no-double-tailwind-execution flake (#86549)
https://github.com/vercel/next.js/runs/56466402435
wait for the `patchFile` revert operation to finish before asserting
```
FAIL webpack test/e2e/app-dir/no-double-tailwind-execution/no-double-tailwind-execution.test.ts (31.136 s)
no-double-tailwind-execution
✕ should run tailwind only once initially and per change (20280 ms)
● no-double-tailwind-execution › should run tailwind only once initially and per change
expect(received).toBe(expected) // Object.is equality
Expected: 3
Received: 2
48 | ].length
49 | if (isNextDev) {
> 50 | expect(tailwindProcessingCount).toBe(3) // dev: initial + hmr + hmr (revert)
| ^
51 | } else {
52 | expect(tailwindProcessingCount).toBe(1) // build
53 | }
at Object.toBe (e2e/app-dir/no-double-tailwind-execution/no-double-tailwind-execution.test.ts:50:39)
```
