[Feature] 13665 date time format not respected

[``* `#13665` Date/Time format not respected``](https://www.openproject.org/work_packages/13665)
[``* `#13664` Timezone not respected``](https://www.openproject.org/work_packages/13664)
If I got you right, you propose ``gon.settings.display[setting] != ''`` becomes ``gon.settings.display[setting] != false``, right?