Google tracker code in org admin edit page has no effect when root organisation has none

[nicolasfranck]

Please complete the following fields as applicable:

What version of the DMPRoadmap code are you running? (e.g. v2.2.0)

4.0.2

Behaviour:

The org admin edit page has an input field for a google analytics tracker code. Unfortunately that field has no effect when the configuration option x.google_analytics.tracker_root is not set to an organisation's abbreviation, and that root organisation does not have a tracker code.

See logic here

So why is the option even presented in the form? Better not disable it when not possible, and show information why? (or simply hide it, that seems configurable)

[briri]

Address when we work on #3090