The dialog was never meant for unconditional workflows (showing all extensions without context ). So it makes no sense to have it available for customization.
So just set all its *Config properties to FALSE in sfx.sdi, and remove its entry from GenericCommands.xcu.
Removing Assignee. No action done in a while
A new major release of LibreOffice is available since this bug was reported.
Could you please try to reproduce it with the latest version of LibreOffice
from https://www.libreoffice.org/download/libreoffice-fresh/ ?
I have set the bug's status to 'NEEDINFO'. Please change it back to
'UNCONFIRMED' if the bug is still present in the latest version.
It's still shown. Perhaps easyhackable though unclear with bug 112620 / bug 147411.
Heiko Tietze committed a patch related to this issue.
It has been pushed to "master":
Resolves tdf#136216 - Hide uno:AdditionsDialog from customization
It will be available in 24.2.0.
The patch should be included in the daily builds available at
https://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More
information about daily builds can be found at:
Affected users are encouraged to test the fix and report feedback.