Bugfix/3477 infinite loading indicator

[mhsdesign]

Resolves: #3477

Alternate fix replaces https://github.com/neos/neos-ui/pull/2566 which is good and we need to make the page handler non neos ui specific so it can go "back" to neos

The initial idea to spin until the ui informs to be ready was that if possibly a lot of ckeditors have to be initialised and that the content manager should wait until the indicator stops spinning before clicking around. IN my problems i could not verify that and as this is just an indicator it does no harm stopping a few milliseconds earlier. It never prevented anything or is used for anything critical. In fact the infinite spinning indicator is much worse when developing and debugging

What I did

How I did it

How to verify it

[neos-bot]

🎥 End-to-End Test Recordings

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These videos demonstrate the end-to-end tests for the changes in this pull request.

[mhsdesign]

@73nici