Add E2E tests for single site environment

[Sidsector9]

Is your enhancement related to a problem? Please describe.

The plugin doesn't work exactly the same between multisite and single site environments. For example $wp->request is defined in the multisite env much earlier compared to single site env.

At the moment, we run Cypress E2E tests only on a multisite env. We need to cover the single site env as well to make the plugin more robust.

A possible solution would be to set up a separate E2E GitHub action for single site.

Designs

No response

Describe alternatives you've considered

No response

Code of Conduct

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