Removed the unused rewire devDependency (#28673)

no ref
- Removes the `rewire` devDependency from `ghost/core` now that every
test that used it has been migrated to sinon object-boundary stubbing.
- Drops a now-stale comment in `model-posts.test.js` that referenced
rewire.

Author: 9larsons

ghost/core/package.json

@@ -300,7 +300,6 @@
     "postcss": "catalog:",
     "postcss-cli": "11.0.1",
     "qs": "6.15.2",
-    "rewire": "9.0.1",
     "sinon": "catalog:",
     "supertest": "catalog:",
     "tmp": "0.2.6",

ghost/core/test/legacy/models/model-posts.test.js

@@ -21,8 +21,6 @@ const markdownToMobiledoc = testUtils.DataGenerator.markdownToMobiledoc;
  * IMPORTANT:
  * - do not spy the events unit, because when we only spy, all listeners get the event
  * - this can cause unexpected behavior as the listeners execute code
- * - using rewire is not possible, because each model self registers it's model registry in bookshelf
- * - rewire would add 1 registry, a file who requires the models, tries to register the model another time
  */
 describe('Post Model', function () {
     let eventsTriggered = {};