This adds a new privacy/services/google_analytics.html template that

enables Google Analytics, but with settings that take advantage of

privacy-protection features like anonymized IP addresses and PII-safe

page titles and URLs. It helps applications that require Google Analytics

keep personally-identifying information safe.
This includes docs for using the service.

Tested with a service making use of this template. Tested the URL

redaction, PII-safe titles, and settings.