Image Block: default caption alignment doesn't match in the editor versus previews/front-end

[designsimply]

Steps to reproduce:

1. Add an image block.
2. Set the image size to Thumbnail.
3. Right-align the image.
4. Add a caption.
5. Compare how the caption looks in the editor to how it looks in previews and the front-end.

Result: the caption is centered by default in the editor view but left-aligned in previews and the front-end.

^{Tested with WPiOS 14.3.0.0 TestFlight beta on iPhone 6S iOS 13.3.1.}

[cameronvoell]

I'm able to replicate this issue in the web editor, so it's likely this is a regression in non-mobile specific code. @designsimply Can you verify you are seeing the issue on WordPress.com web as well? (not sure if I have some theme breaking this or if all captions are aligned incorrectly on WordPress.com at the moment).

If you see the issue on web as well then maybe we can troubleshoot alongside gb core team. I found this issue that they might be using to track this issue, but it seems odd that image caption alignment is uncentered everywhere and we didn't notice sooner.

[mchowning]

👋 @designsimply ! I'm seeing that the caption now has center alignment under the caption on the preview as well.

Editor	Preview

Do you think there is still an issue here? There is obviously a difference between how the paragraph and caption text is laid out in the editor compared to the frontend, but the alignment seems to match now and I think the other issues may be covered by #1954.