Fix browser imports in examples

[ankur22]

What?

This fixes a few browser imports in the browser module examples from:

import { chromium } from 'k6/experimental/browser';

to:

import { browser } from 'k6/experimental/browser';

Checklist

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Select one of these and delete the others:

If updating the documentation for the most recent release of k6:

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If updating the documentation for the next release of k6:

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Related PR(s)/Issue(s)

[inancgumus]

Nice :)