refactor: simplify artifact package and rename some functions to make it more explicit

The following discussion from !787 (merged) should be addressed:

• @bwill started a discussion: (+3 comments)

  Reading the rest of the code, I actually don't understand why we're doing all this, because we're essentially cloning this request by pulling the fields out and then rebuilding it again with http.NewRequestWithContext. Normally I would suggest doing r.Clone(newContext) if we wanted to create a copy with a new context, but it looks like we're even passing the existing request context to NewRequestWithContext, so it's a complete clone. How about we remove all of that?

  diff --git a/internal/artifact/artifact.go b/internal/artifact/artifact.go
  index 87ce1450..9e1633a3 100644
  --- a/internal/artifact/artifact.go
  +++ b/internal/artifact/artifact.go
  @@ -17,7 +17,6 @@ import (
   	"gitlab.com/gitlab-org/gitlab-pages/internal/httperrors"
   	"gitlab.com/gitlab-org/gitlab-pages/internal/httptransport"
   	"gitlab.com/gitlab-org/gitlab-pages/internal/logging"
  -	"gitlab.com/gitlab-org/gitlab-pages/internal/request"
   )
   
   const (
  @@ -67,27 +66,12 @@ func (a *Artifact) TryMakeRequest(w http.ResponseWriter, r *http.Request, token
   		return false
   	}
   
  -	host := request.GetHostWithoutPort(r)
  -
  -	reqURL, ok := a.BuildURL(host, r.URL.Path)
  -	if !ok {
  -		return false
  -	}
  -
  -	a.makeRequest(w, r, reqURL, token, additionalHandler)
  +	a.makeRequest(w, r, token, additionalHandler)
   
   	return true
   }
   
  -func (a *Artifact) makeRequest(w http.ResponseWriter, r *http.Request, reqURL *url.URL, token string, additionalHandler func(*http.Response) bool) {
  -	req, err := http.NewRequestWithContext(r.Context(), "GET", reqURL.String(), nil)
  -	if err != nil {
  -		logging.LogRequest(r).WithError(err).Error(createArtifactRequestErrMsg)
  -		errortracking.CaptureErrWithReqAndStackTrace(err, r)
  -		httperrors.Serve500(w)
  -		return
  -	}
  -
  +func (a *Artifact) makeRequest(w http.ResponseWriter, req *http.Request, token string, additionalHandler func(*http.Response) bool) {
   	if token != "" {
   		req.Header.Add("Authorization", "Bearer "+token)
   	}
  @@ -98,8 +82,8 @@ func (a *Artifact) makeRequest(w http.ResponseWriter, r *http.Request, reqURL *u
   			return
   		}
   
  -		logging.LogRequest(r).WithError(err).Error(artifactRequestErrMsg)
  -		errortracking.CaptureErrWithReqAndStackTrace(err, r)
  +		logging.LogRequest(req).WithError(err).Error(artifactRequestErrMsg)
  +		errortracking.CaptureErrWithReqAndStackTrace(err, req)
   		httperrors.Serve502(w)
   		return
   	}
  @@ -116,8 +100,8 @@ func (a *Artifact) makeRequest(w http.ResponseWriter, r *http.Request, reqURL *u
   	}
   
   	if resp.StatusCode == http.StatusInternalServerError {
  -		logging.LogRequest(r).Error(errArtifactResponse)
  -		errortracking.CaptureErrWithReqAndStackTrace(errArtifactResponse, r)
  +		logging.LogRequest(req).Error(errArtifactResponse)
  +		errortracking.CaptureErrWithReqAndStackTrace(errArtifactResponse, req)
   		httperrors.Serve500(w)
   		return
   	}

  We can use (*http.Request).Clone() if we really need a copy, but I don't see why we'd need one.