Rationalise sales-dashboard and Organisation Settings to pull seat data from Chargebee

[dabeeeenster]

Where organisations have a paid subscription in Chargebee, we should use the Chargebee meta data to display seat count and max api calls.

This should replace pulling the data directly from the postgres table organisation_subscription

[gagantrivedi]

Yep, we already do that for seats, api calls and projects

[dabeeeenster]

Can we also use CB data for the Sales Dashboard overview table @gagantrivedi

[dabeeeenster]

Just needs data for overview table to read from CB API