Hi Strainu,
indeed there is no policy about (not) allowing links from
CentralNotice banners to websites using third party analytics systems,
just as I wrote in my offlist e-mail to you.
I can only provide you with an opinion of a Wikimedia Foundation Legal
and Community Advocacy team member, who is deeply uncomfortable about
us linking to websites using Google Analytics, and therefore giving
our users' very sensitive data to a third company for free.
I would very much like to avoid any controversies and arguments with
regard to this subject; we have installed and configured Piwik for
your use specifically to keep our users' data safe, and am (yet again)
urging you to do use this opportunity.
Tomasz