Don't run @ember/owner polyfill on ember-source itself

With ember-cli#323 landed, `ember-lts-4.12` flips to:

    Uncaught ReferenceError: Cannot access 'getOwner' before initialization
    at app-*.js line N

ember-source >= 4.12's `@ember/application/index.js` re-exports the real
implementations from `@ember/owner` as aliases:

    import { getOwner as actualGetOwner, setOwner as actualSetOwner }
      from '@ember/owner';
    export const getOwner = actualGetOwner;
    export const setOwner = actualSetOwner;

`babel-plugin-ember-polyfill-get-and-set-owner-from-ember-owner` rewrote
the source of that import to `@ember/application` — turning the module
into a self-import that rollup then collapses into
`const getOwner = getOwner` (TDZ).

The plugin already tries to skip ember-source paths, but the guard only
short-circuits when the file is outside `.embroider/`; in a vite
compat build ember-source lives at
`node_modules/.embroider/rewritten-packages/ember-source.*/` so it
fell through and got rewritten. Gate the plugin through babel
`overrides` with a `test` filter that excludes any path containing
`/ember-source/`. The polyfill still runs where it needs to
(e.g. `@glimmer/[email protected]`'s `import { setOwner } from
'@ember/owner'`, which is how min-supported started passing in ember-cli#323).

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

Author: NullVoxPopuli

test-app/babel.config.mjs

@@ -54,11 +54,22 @@ export default {
               flags: [{ source: '@glimmer/env', flags: { DEBUG: true } }],
             },
           ],
-          'babel-plugin-ember-polyfill-get-and-set-owner-from-ember-owner',
         ]
       : []),
   ],
 
+  overrides: isCompatBuild
+    ? [
+        {
+          test: (filename) =>
+            filename !== undefined && !filename.includes('/ember-source/'),
+          plugins: [
+            'babel-plugin-ember-polyfill-get-and-set-owner-from-ember-owner',
+          ],
+        },
+      ]
+    : [],
+
   generatorOpts: {
     compact: false,
   },