RED-3691 Fix GTM causing video to not load

[shadinaif]

Change description

Unlike other integration scripts, Google Tag Manager is in body-initial.html instead of body-extra.html. This is to move it to body-extra.html because it's causing video loading to fail sometimes. See the upstream discussion regarding the issue here

Type of change

• [x] Bug fix (fixes an issue)
• [ ] New feature (adds functionality)

Related issues

Fixes: https://appsembler.atlassian.net/browse/RED-3691 Upstream discussion: https://discuss.openedx.org/t/first-video-on-lesson-dont-work/3836/4

Checklists

Development

• [ ] Lint rules pass locally
• [ ] Application changes have been tested thoroughly
• [ ] Automated tests covering modified code pass

Security

• [ ] Security impact of change has been considered
• [ ] Code follows company security practices and guidelines

Code review

• [ ] Pull request has a descriptive title and context useful to a reviewer. Screenshots or screencasts are attached as necessary
• [ ] "Ready for review" label attached and reviewers assigned
• [ ] Changes have been reviewed by at least one other contributor
• [ ] Pull request linked to task tracker where applicable