Get the proper Subversion URI for hosted repositories.

Summary: The commit change parser worker was incorrectly getting the remote uri; calling getSubversionPathURI instead behaves properly for hosted repositories. Fixes T4236.

Test Plan: Observed that my hosted subversion repositories finally had history in Diffusion.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley

CC: Korvin, epriestley, aran

Maniphest Tasks: T4236

Differential Revision: https://secure.phabricator.com/D7794