Revert "sysusers.d: create the user for systemd-journal-upload.service"

Revert "sysusers.d: create the user for systemd-journal-upload.service"

I have no idea what was my reasoning that led to this change, but it is
simply wrong: systemd-journal-upload.service uses
User=systemd-journal-upload together with DynamicUser=yes, so the user
doesn't have to (and shouldn't) exist before starting the service.

See:
  - https://github.com/systemd/systemd/commit/941afc4b902af21b0675e9e5d417c2ee6b202f30
  - https://src.fedoraproject.org/rpms/systemd/c/db8b8fe77ce30244ad82e70ec4e8302b0c9dbf41

This reverts commit 5b9dfd33c6cd4d32ee1fd3681b570e09401c885d.