test: rewrite waitForNavigation to waitForEvent('load')

[sapphi-red]

Description

waitForNavigation is deprecated. The document suggests to use waitForURL but that doesn't work for reloads. This PR replaces waitForNavigation with waitForEvent('load')

waitForURL resolves immediately if the page is already showing that URL.

Additional context

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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• Read the Contributing Guidelines.
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