fix(test): mock hashtagPreferencesService.load in profile modal tests

- Updates `tests/profile-modal-controller.test.mjs` to include a mock for `load()` in `baseHashtagPreferences`.
- Resolves the `TypeError: this.hashtagPreferencesService.load is not a function` error seen in CI.
- Ensures unit tests pass for ProfileModalController interactions with the hashtag pane.

Co-authored-by: PR0M3TH3AN <[email protected]>

tests/profile-modal-controller.test.mjs

@@ -275,6 +275,7 @@ function createController(options = {}) {
     },
     publish: async () => ({ ok: true }),
     on: () => () => {},
+    load: async () => {},
   };
 
   const hashtagPreferences = {