Fix gif and video issues

[alexandratran]

Description

Fix gif and video issues as appearing on these pages:

• https://docs.metamask.io/snaps/features/custom-ui/
• https://docs.metamask.io/wallet/concepts/sdk/#user-experience (unity tab)

Caused by changes in this PR: https://github.com/MetaMask/metamask-docs/pull/1250

Preview

• https://docs.metamask.io/fix-spinner-gif/snaps/features/custom-ui/
• https://docs.metamask.io/fix-spinner-gif/wallet/concepts/sdk/#user-experience

Checklist

Complete this checklist before merging your PR:

• [ ] If this PR contains a major change to the documentation content, I have added an entry to the top of the "What's new?" page.
• [ ] The proposed changes have been reviewed and approved by a member of the documentation team.

[github-actions[bot]]

Preview published: fix-spinner-gif