Revert "Move default media files to regional storage (#2407)"

[malincrist]

This reverts commit 4a51397.

Problem

After moving the default media file to regional containers, it was identified that, before the first publishing, they are not accessible by the publisher.
This is happening because Developer Portal returns the text with Learn more and instructions for publishing by default, when there is no revision. This default text is also returned instead of the images, hence they cannot be copied to tenant storage.

Solution

Revert the changes for now.

[github-actions]

Accessibility Insights Action: All applicable checks passed

• URLs: 13 URL(s) passed, and 0 were not scannable
• Rules: 29 check(s) passed, and 23 were not applicable
• Download the Accessibility Insights artifact to view the detailed results of these checks

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This scan used axe-core 4.3.2 with Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.75 Safari/537.36.