test: remove a misplaced assertion

1. This assertion is already included in another test.

2. Considering the title of the test "it defers the boot of the app",
   this assertion does not belong here.

tests/unit/initializers/embedded-test.ts

@@ -144,12 +144,6 @@ module('Unit | Initializer | embedded', function (hooks) {
       'A `start()` method has been added'
     )
 
-    assert.deepEqual(
-      this.application.resolveRegistration('config:embedded'),
-      undefined,
-      'The embedded config is not registered until the app is started'
-    )
-
     assert.false(this.application._booted, 'The app has not booted')
 
     assert.strictEqual(