(stable) Strip "Transfer-Encoding" headers from proxied HTTP responses
(stable) Strip "Transfer-Encoding" headers from proxied HTTP responses

This is a likely fix for HTTP clones against proxied repositories in the
cluster, although I'm not 100% sure I'm replicating it correctly.

The issue appears to be that we're proxying all the headers, including the
"Transfer-Encoding" header, although the request will already have stripped
any encoding. This might cause us to emit a "chunked" header without a
chunked body.

Auditors: chad

Automatic/phabricator,wikimedia/phabricator,wikimedia/phabricator-phabricator,uhd-urz/phabricator,wikimedia/phabricator-phabricator,aik099/phabricator,wikimedia/phabricator,r4nt/phabricator,r4nt/phabricator,wikimedia/phabricator-phabricator,r4nt/phabricator,r4nt/phabricator,wikimedia/phabricator,uhd-urz/phabricator,wikimedia/phabricator-phabricator,wikimedia/phabricator-phabricator,Automatic/phabricator,uhd-urz/phabricator,devurandom/phabricator,uhd-urz/phabricator,devurandom/phabricator,cjxgm/p.cjprods.org,cjxgm/p.cjprods.org,Automatic/phabricator,cjxgm/p.cjprods.org,uhd-urz/phabricator,aik099/phabricator,r4nt/phabricator,Automatic/phabricator,devurandom/phabricator,devurandom/phabricator,aik099/phabricator,cjxgm/p.cjprods.org,devurandom/phabricator,aik099/phabricator,devurandom/phabricator,gsinkovskiy/phabricator,wikimedia/phabricator,gsinkovskiy/phabricator,gsinkovskiy/phabricator,gsinkovskiy/phabricator,gsinkovskiy/phabricator,cjxgm/p.cjprods.org