R1:ca6da4c2befe

When proxying the SVN protocol, don't mutate URIs in protocol frames if we're an intracluster proxy

Summary:
Ref T10809. Currently, both the proxy and target may mutate URIs (rewriting "svn+ssh://x/diffusion/Y/" to a path on disk).

I believe this previously worked by fate/chance/luck since both URI variants contain the repository information, but the algorithms were tightened up recently with callsign removal.

Stop rewriting them if we're the intracluster proxy -- they only need to be rewritten on the…