Remove user_agent_map from pageview_hourly long term
A much reduced version of this data is available as part of https://wikitech.wikimedia.org/wiki/Analytics/Data/Browser_general (with e.g. URL, project, referrer class and geographical information removed). The user_agent map per url is useful in the 90 day period when it help us troubleshoot ops issues, and has been used beyond that period in various other analyses.
See:
https://wikitech.wikimedia.org/wiki/Analytics/Data/Pageview_hourly/Identity_reconstruction_analysis