internal/auth: remove authn annotator

gRPC Gateway performs this automatically.

Signed-off-by: Jimmy Zelinskie <jimmy@zelinskie.com>

internal/auth/presharedkey.go

@@ -5,10 +5,8 @@ import (
 	"crypto/subtle"
 	"errors"
 	"fmt"
-	"net/http"
 
 	grpcauth "github.com/grpc-ecosystem/go-grpc-middleware/auth"
-	"google.golang.org/grpc/metadata"
 )
 
 const errInvalidPresharedKey = "invalid preshared key: %w"
@@ -31,16 +29,3 @@ func RequirePresharedKey(presharedKey string) grpcauth.AuthFunc {
 		return ctx, nil
 	}
 }
-
-// PresharedKeyAnnotator copies the Authorization header from an HTTP request
-// and sets it on the gRPC context.
-func PresharedKeyAnnotator(ctx context.Context, r *http.Request) metadata.MD {
-	md, ok := metadata.FromIncomingContext(ctx)
-	if ok {
-		md = md.Copy()
-	} else {
-		md = metadata.New(map[string]string{})
-	}
-	md.Append("authorization", r.Header.Get("Authorization"))
-	return md
-}