Revert "Disable systemd-boot-update.service in presets"
    
    This reverts commit 8eea43e7149ba2f23062995d3bf83ebab0271274.
    
    Fedora already ships 'disable systemd-boot-update.service' in
    /usr/lib/systemd/system-preset/90-default.preset, so we don't need
    this.
    
    [skip changelog]