Remove outdated statement that browsers tend to handle the `popstate` event differently on page load (#43373)

* Update popstate event handling details #43368

Updated the section on the handling of popstate event on page load across different browsers.

Closes https://github.com/mdn/content/issues/43368

* Update files/en-us/web/api/window/popstate_event/index.md

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

* Remove outdated information about popstate event handling on page load.

based on review comment https://github.com/mdn/content/pull/43373#pullrequestreview-3915343863

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Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>