[FEAT]: Too many charts show up as thumbnail of the "Create intervention policy" operator - should user-selected and/or capped

[liunelson]

Describe the bug

The SIDARTHE model is an example of a modelling use case where the intervention policy intervened on a lot of parameters.

The "Create intervention policy" operator currently puts one chart per intervened parameter as thumbnail. This looks crazy in the workflow view.

We could have the user select what they want to see as thumbnail or just capped the number to 2-3.

[YohannParis]

The solution is to display the written version of the intervention policy instead of the charts.

for example what we display in simulate operator.