Issue/1592 fix alignment hiding image placeholder

[mchowning]

Fixes #1592

This fixes a bug that was introduced with the addition of paragraph alignment options. In particular, the placeholder icon would not display for an aligned image block if the image could not be downloaded.

Related gutenberg PR

To test:

• Create a draft post on web with aligned images
• Open an empty post in the app (to load the js from the metro bundler)
• Go to the list of draft posts in the app so that the newly created draft is loaded
• Turn on airplane mode
• Open the draft post
• Observe that all of the image blocks have visible placeholder images

Update release notes:

• If there are user facing changes, I have added an item to RELEASE-NOTES.txt.

[etoledom]

Approved via WordPress/gutenberg#18793 (review) 🎉

[etoledom]

This should probably go to 1.20.0.

[designsimply]

LGTM! (here is a screenshot from beta testing)

^{Tested with WPAndroid 14.0-rc-1 on Pixel 3 Android 10.}