Revert "Delete vendor/ and the route proxy's: the build module fetches the modules, the root image builds with -mod=mod (issue 1305, C6)"

This reverts commit 9c4bf1f08b.

internal/testbus/testbus_test.go

@@ -22,7 +22,7 @@ func TestTheBusTheTestsRunIsTheBusTheMeshRuns(t *testing.T) {
 	release, from := catalogueBusRelease(t, filepath.Join(beside.Catalogue(t), "nats"))
 	if release != Version {
 		t.Errorf("the tests run bus %s and the catalogue's bus image is %s (%s): move go.mod's nats-server pin "+
-			"with the image", Version, release, from)
+			"(and `go mod vendor`) with the image", Version, release, from)
 	}
 	path := os.Getenv("MESH_FACTS")
 	if path == "" {