Reverting passthrough auth (#1700)

* Reverting PR 1650

https://github.com/gomods/athens/pull/1650 was a big change to the
authentication/authorization code, which we have decided to pull
out and potentially move into a separate process/project

Signed-off-by: Aaron Schlesinger <aaron@ecomaz.net>

* removing commented, unused code

Signed-off-by: Aaron Schlesinger <aaron@ecomaz.net>

* removing more commented, unused code

Signed-off-by: Aaron Schlesinger <aaron@ecomaz.net>

* removing more unused code

Signed-off-by: Aaron Schlesinger <aaron@ecomaz.net>

pkg/stash/stasher.go

@@ -4,7 +4,6 @@ import (
 	"context"
 	"time"
 
-	"github.com/gomods/athens/pkg/auth"
 	"github.com/gomods/athens/pkg/errors"
 	"github.com/gomods/athens/pkg/index"
 	"github.com/gomods/athens/pkg/log"
@@ -53,12 +52,8 @@ func (s *stasher) Stash(ctx context.Context, mod, ver string) (string, error) {
 
 	// create a new context that ditches whatever deadline the caller passed
 	// but keep the tracing info so that we can properly trace the whole thing.
-	tok, ok := auth.FromContext(ctx)
 	ctx, cancel := context.WithTimeout(trace.NewContext(context.Background(), span), time.Minute*10)
 	defer cancel()
-	if ok {
-		ctx = auth.SetAuthInContext(ctx, tok)
-	}
 	v, err := s.fetchModule(ctx, mod, ver)
 	if err != nil {
 		return "", errors.E(op, err)