[CORL-2611]: update external media width in comments

[kabeaty]

trafficstars

What does this PR do?

These changes update the width of external media images within comments. The widths now match what we are doing for Youtube (75% width on desktop, 100% width on mobile).

What changes to the GraphQL/Database Schema does this PR introduce?

none

Does this PR introduce any new environment variables or feature flags?

no

If any indexes were added, were they added to INDEXES.md?

n/a

How do I test this PR?

Add images to your comments. See that they are shown at 75% width on desktop and 100% width on mobile in the stream. Also take a look at comments with images in the admin; their widths have been updated to just be 100%.

How do we deploy this PR?

[netlify[bot]]

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