The text, flow text, and log markers all carry developer-provided free-text fields that might embed URLs. These fields were declared with MS::Format::String, which the profiler front-end doesn't sanitize. Switch these fields to MS::Format::UniqueString so their contents are added to the profile's shared string table. The front-end runs removeURLs over the whole string table when sanitizing. Differential Revision: https://phabricator.services.mozilla.com/D311475