Refactor middleware to stop resolving a domain name when is not needed

We don't need to resolve a domain's configuration for every request, some cases are:

This happens due to the order of middleware execution, see gitlab#25192 (comment 678799178) for details.

The following discussion from !585 (merged) should be addressed:

@jaime started a discussion: (+2 comments)

I would love to fix gitlab#25192 (comment 678799178) here, where we try to resolve a domain as the first thing in the request chain, and sometimes is not necessary, for example when proxying artifacts.