With firstcontributions/first-contributions#32256, We've moved assets we need in our tutorials to https://github.com/firstcontributions/assets. Now we should use them.

🎯 Goal
Replace usage of assets in this repository to assets repository to reduce the size of this repo.

💡 Possible solutions

Following the files in which you have to change asset URLs

Introduction

Background

To ensure Oppia remains available and high-quality for our students, we run end-to-end tests on all PRs to check that the site's functionality hasn't been broken. Recently, these tests have begun failing non-deterministically. This frustrates developers and slows their work by incorrectly indicating that developers’ changes are faulty. The goal of this issue is t