[5.0] Fix com_ajax event with webauthn plugin

[Fedik]

Pull Request for Issue #41719.

Summary of Changes

Fix com_ajax event with webauthn plugin ajax requests

Testing Instructions

Please follow #41719

Actual result BEFORE applying this Pull Request

error

Expected result AFTER applying this Pull Request

no error

Link to documentations

Please select:

• Documentation link for docs.joomla.org:
• No documentation changes for docs.joomla.org needed
• Pull Request link for manual.joomla.org:
• No documentation changes for manual.joomla.org needed

[heelc29]

I have tested this item ✅ successfully on 69bdf91

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/41720.}

[HLeithner]

That's not the best way and we need a more generic way for 3rd party events but for now it fixes the issue.