Hi,
while we are still waiting for blocking triggers to come true in Piwik PRO tag manager, you would have to adjust all firing triggers to contain an additional condition that only allows tags to be triggered when there is no “blocking cookie”… If you want to prevent the data to be created instead of segmenting out internal users from reports by using a dimension with that cookie value.
As an example: You can add a custom HTML tag that creates a cookie “internal” with the value “true” whenever a URL contains a param “internal=1”. This tag can fire on every page under that condition, as early as possible. If someone wants to set this cookie, just add “?internal=1” to any URL on your site and the cookie will be created and live as long as the browser allows. Add the parameter to a bookmark that you use to open your own website to make sure the cookie is refreshed every time you enter.
But: adjusting all existing triggers can be hard. Populating a dimension is easy - pick your favourite or wait for blocking triggers 
Hope that helps,
best
Markus