feat(api): set tmdb query's default language based on locale setting

[fallenbagel]

Description

From PR#627. Re-opening a PR with a cherrypick because not sure why cypress tests were failing, so to test.

The tmdb api's default language is en, there's locale issue in notification payload. Since the locale is set from settings, just get the value there.

Screenshot (if UI-related)

To-Dos

• Successful build yarn build
• Translation keys yarn i18n:extract
• Database migration (if required)

Issues Fixed or Closed

• Fixes ###