TASK: Remove i18n labels that are obsolete after neos/neos-ui#3759

[grebaldi]

The publishing workflow in the UI has changes significantly with https://github.com/neos/neos-ui/pull/3759 and requires an entirely new set of labels. Those labels are now located in the UI repository.

The following labels are therefore obsolete after https://github.com/neos/neos-ui/pull/3759 gets merged:

• Neos.Neos:Main:content.components.discardAllDialog.discardXChangesSubheader
• Neos.Neos:Main:content.components.discardAllDialog.discardAllChangesHeader
• Neos.Neos:Main:content.components.discardAllDialog.discardAllChangesSubheader
• Neos.Neos:Main:content.components.publishAllDialog.header
• Neos.Neos:Main:content.components.publishAllDialog.subheader

This PR removes these labels from all translation files.

Marked as draft as long as https://github.com/neos/neos-ui/pull/3759 is still open