[TEST][Gutenberg] Flatten inner blocks to fix call stack size exceeded crash

[fluiddot]

Fixes #

To test:

Regression Notes

1. Potential unintended areas of impact

2. What I did to test those areas of impact (or what existing automated tests I relied on)

3. What automated tests I added (or what prevented me from doing so)

PR submission checklist:

• I have completed the Regression Notes.
• I have considered adding unit tests for my changes.
• I have considered adding accessibility improvements for my changes.
• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

UI Changes testing checklist:

• Portrait and landscape orientations.
• Light and dark modes.
• Fonts: Larger, smaller and bold text.
• High contrast.
• VoiceOver.
• Languages with large words or with letters/accents not frequently used in English.
• Right-to-left languages. (Even if translation isn’t complete, formatting should still respect the right-to-left layout)
• iPhone and iPad.
• Multi-tasking: Split view and Slide over. (iPad)

[peril-wordpress-mobile]

	Fails
🚫	This PR is tagged with '[Status] DO NOT MERGE' label.

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[wpmobilebot]

📲 You can test the changes from this Pull Request in WordPress Alpha by scanning the QR code below to install the corresponding build.

	App Name	WordPress Alpha
	Configuration	Release-Alpha
	Build Number	pr21552-90aad51
	Version	23.2
	Bundle ID	org.wordpress.alpha
	Commit	90aad51
	App Center Build	WPiOS - One-Offs #7043

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[wpmobilebot]

📲 You can test the changes from this Pull Request in Jetpack Alpha by scanning the QR code below to install the corresponding build.

	App Name	Jetpack Alpha
	Configuration	Release-Alpha
	Build Number	pr21552-90aad51
	Version	23.2
	Bundle ID	com.jetpack.alpha
	Commit	90aad51
	App Center Build	jetpack-installable-builds #6087

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[mokagio]

@fluiddot I'm going to close this given there hasn't been any activity in a long time and it looks like a test PR anyway. Feel free to reopen if needed.