fix a CI todo and some cleanup
- main point:
Issue 273034 closed since I last had a look this allows to generate nighly and test versions under the same package as releases, but with the version containing a corresponding label and build metadata - cleanup changes that should have been part of 5d67c555
- fixed new release using the wrong date format (yyyy-mm-dd instead of dd/mm/yyyy)
- also move the link generation for nightly from
update_version.sh
torelease_helper.sh
(as 5d67c555 did for release)