Removing DEV flag for Image block size options

[cameronvoell]

Fixes #1329

Description

We recently finished resolving behavioral issues related to updating images sizes on mobile, and are therefore removing the DEV flag blocking the feature in non-development builds.
See - #1593

Related PRs:

• Gutenberg: [RNMobile] Removing DEV flag for Image block size options WordPress/gutenberg#20229
• WPiOS (for testing only) - Gutenberg - Testing image size options WordPress-iOS#13462
• WPAndroid (for testing only) - Gutenberg - Testing image size options WordPress-Android#11305

Screenshot

To test

(Changes tested in individual PRs from #1593):
(Must be tested in WP Apps, see test PRs above)

1. Add an Image Block and upload an image
2. Click the gear for block settings
3. Tap Image Size row and verify value cycles through available sizes (Thumbnail, Medium, Large, Fullscreen).
4. Verify the Image size changes as you click through the menu.
5. Verify the Image Size is preserved if you update the post, leave, and return.

PR submission checklist:

• I have considered adding unit tests where possible.
• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

[etoledom]

Thank you @cameronvoell for this!
Changes look good, but I'm investigating the failing tests on wordpress-mobile/WordPress-iOS#13462

It doesn't seem to be related to this particular PR, but I'd be more confident to merge after this is figured out.

[etoledom]

So, the UI Tests failure on WPiOS will be fixed separately and has no relation with this PR.

Lets ! 🎉
Thank you @cameronvoell 🙏

Let's also revert the bundles before merging this PR.

[cameronvoell]

Bundle update reverted, and gutenberg reference updated., merging!