Censor URIs in service profile log

Summary: Mailgun requests can hit a credentialed URI. Censor credentials from --trace URIs.

Test Plan: Ran bin/mail send-test ... --trace and saw censored credentials.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Differential Revision: https://secure.phabricator.com/D8833