Dynamically truncate requests for Matomo report data

[diosmosis]

Looker Studio requests for data are bounded by App Script's limitations. Specifically, they can only run for a certain amount of minutes before being aborted.

If Matomo takes too long to process and return this data, the request will simply fail. Right now the only workaround is to set the "Default Row Limit" setting to limit the amount of data that is queried. But this option requires guess work from the user and is likely an annoying user experience.

Instead, we should explore dynamically truncating report data (using filter_truncate) when we know we're about to run out of time. This will at least show users the data they're expecting.