Add PII-safe titles for the user pages.
Review Request #9944 — Created May 15, 2018 and submitted
This adds a context variable for the user pages that provide PII-safe
titles for use in services like Google Analytics. These titles are
stripped of usernames, and just provide a generic page title to go with
what will be a generic URL.
Manually tested that the Google Analytics template was passing in the
PII-safe titles for these pages.