Ensure OpenID related responses aren't cached by proxies

We should never cache a reply coming from an OpenID related exchange
as there may be a cookie header embedded in it.

Signed-off-by: Shawn O. Pearce <sop@google.com>

src/main/java/com/google/gerrit/server/rpc/OpenIdServiceImpl.java

@@ -219,6 +219,8 @@ class OpenIdServiceImpl implements OpenIdService {
       debugRequest(req);
     }
 
+    callFactory.get().noCache();
+
     final String openidMode = req.getParameter(OPENID_MODE);
     if (OMODE_CANCEL.equals(openidMode)) {
       cancel(req, rsp);