Setting `isTesting = true` in `enterTestMode()` is too late

Hello,

I'm playing with `--no-compat` mode, and found that current setup of `isTesting` macro is done too late.

Because `macroCondition(isTesting())` can be called _everywhere_ eq. app/add-on module's scope, it seems necessary to setup macros before any import of app/add-on code.

Using following example worked for me, does this make sense?

```html

window._embroider_macros_runtime_config ??= [];
window._embroider_macros_runtime_config.push((config) => {
config.getGlobalConfig()["@embroider/macros"].isTesting = true;
});

import { start } from './test-helper';
import.meta.glob("./**/*.{js,ts,gjs,gts}", { eager: true });
start();

```