As a developer and product manager, I don't want matomo metrics being sent by development instances used by developers

Currently matomo is receiving data from controlcenter instances used by developers, which pollutes the data from the users, as both kinds are mixed.

We should provide a way to make sending metrics optional and disabled by default when running by us developers.

To be discussed in a different story: should we offer a opt-out for normal users (or show a "data policy" popup window?).