[test] app-basepath less agressive request reading (#86740)
Hopefully helps with this
```
● app dir - basepath › should properly stream an internal server action redirect() with a relative URL
request.allHeaders: Target page, context or browser has been closed
77 | beforePageLoad(page) {
78 | page.on('request', (request) => {
> 79 | return request.allHeaders().then((headers) => {
| ^
80 | if (
81 | headers['rsc'] === '1' &&
82 | // Prefetches also include `rsc`
at Page.allHeaders (e2e/app-dir/app-basepath/index.test.ts:79:28)
```
