fix/3239/3268 image default width

[Arukuen]

fixes #3268 fixes #3239

Note that this PR can satisfy the feature of #3239 since the default image width in the units of px is chaged from a default of 300px to the original width of the image.

[github-actions[bot]]

🤖 Pull request artifacts

file	commit
pr3270-stackable-3270-merge.zip	e3ae2ac2e95c2af13267fd8c1e4edc996c153369

[github-actions[bot]]

Try this Pull Request in the WordPress playground: https://playground.wordpress.net/?mode=seamless#{"landingPage":"/wp-admin/post-new.php?post_type=page","preferredVersions":{"php":"latest","wp":"latest"},"steps":[{"step":"login","username":"admin","password":"password"},{"step":"installPlugin","pluginZipFile":{"resource":"url","url":"https://raw.githubusercontent.com/gambitph/Stackable/artifacts/pr3270-stackable-3270-merge.zip"}}]}

[bfintal]

Changing the default width doesn't fix the issue since uploading a small image would still stretch them. Closing this in favor of #3403