[#76768770] Cookie/Set-Cookie should be cached

#### Set-Cookie responses should be cached

Move this test from TestNoCache to TestCache. The RFC states:
http://tools.ietf.org/html/rfc7234#section-8

> Note that the Set-Cookie response header field [RFC6265] does not
> inhibit caching; a cacheable response with a Set-Cookie header field
> can be (and often is) used to satisfy subsequent requests to caches.
> Servers who wish to control caching of these responses are encouraged
> to emit appropriate Cache-Control response header fields.

This passes on CloudFlare. We'll need to modify our Fastly configs to remove
a section of config that we copied from the UI-generated config.

#### Cookie requests should be cached

Move this test from TestNoCache to TestCache. Most sites set cookies, either
by Set-Cookie responses from origin or client-side javascript, and they will
provide a Cookie header in each request. If we weren't to cache these then
nearly all traffic would hit origin. This matches the default behaviour of
Fastly and CloudFlare.