Switch to old UI button leads to 404

[aertmann]

Description

The legacy UI switch code was removed in #2307, however the button still appears in the new UI when the configuration is enabled.

Steps to Reproduce

1. Set configuration Neos.Neos.Ui.frontendConfiguration.legacy.enableUiSwitch to true
2. Click button in dropdown menu in new UI

Expected behavior

To redirect to the old UI or the button not to exist.

Actual behavior

Button exists and leads to a page not found (404).

Affected Versions

Neos: 4.2

UI: 3.0.1

[dimaip]

@daniellienert that's what I was trying to remember when reviewing you PR :)

[danielkestler]

IMO we can maybe remove this button in the meantime.

[daniellienert]

I guess so.