[blog] Remove default social card

[oliviertassinari]

Put #32257 (comment) in motion. See how it feels better, more focus on the content of the tweet, no useless generic text message "The React UI library you always wanted" makes no sense to me in the context of a tweet 😌:

With a custom social image

Same as before: great, no distraction from the content of the tweet, only an illustration to make the tweet more appealing:

Without a custom social image

Before: bad, the text of the image moves the attention away from the important message of the Tweet.

https://mui.com/blog/callback-support-in-style-overrides/

After: not great, but not bad either.

https://deploy-preview-32536--material-ui.netlify.app/blog/callback-support-in-style-overrides/

Related to #32036

[mui-bot]

No bundle size changes

Generated by 🚫 dangerJS against 7f12b4b

[danilo-leal]

Nice! I might try to add a social card preview for all blog posts we have retroactively at some point :) But this works well for now!

[oliviertassinari]

The only counter-argument to this change I can think of this option C would work better:

Option C: create a generic visual for the blog posts. Something with no text to distract the attention. The advantage would be that we would still use a lot of screen real-estate with our blog post tweet.

Maybe it's an option that @samuelsycamore would prefer 🤷‍♂️. I'm happy either. This advantage of this PR (Option B), is that it's less work, and gives us an extra incentive to add a personalized visual to each blog post. I might like B better than C (Option A is current state on master)