Accordion Header: use withoutInteractiveFormatting instead of hardcoded formats

[nani-samireddy]

What?

Closes #71741

This PR updates the Accordion Header block to use the withoutInteractiveFormatting prop in RichText, instead of hardcoding a limited list of allowedFormats.

Why?

Currently, the Accordion Header places a RichText component inside a .
This code does not prevent the insertion of interactive elements, as consumers may add custom formatting.

Using withoutInteractiveFormatting ensures that only safe, non-interactive text formats (bold, italic, strikethrough, etc.) are allowed, and interactive content tags are automatically blocked. This makes the block more robust and future-proof.

How?

Removed the hardcoded allowedFormats array.
Added withoutInteractiveFormatting to the Accordion Header’s RichText component.
No change in the user experience for text styling

Testing Instructions

1. Create or edit a post or page.
2. Insert an Accordion block.
3. Add text to the Accordion Header.
4. Try applying basic formatting (bold, italic, strikethrough) → ✅ works.
5. Try inserting interactive elements such as links or media → ❌ not allowed.

[github-actions]

Warning: Type of PR label mismatch

To merge this PR, it requires exactly 1 label indicating the type of PR. Other labels are optional and not being checked here.

• Type-related labels to choose from: [Type] Automated Testing, [Type] Breaking Change, [Type] Bug, [Type] Build Tooling, [Type] Code Quality, [Type] Copy, [Type] Developer Documentation, [Type] Enhancement, [Type] Experimental, [Type] Feature, [Type] New API, [Type] Task, [Type] Technical Prototype, [Type] Performance, [Type] Project Management, [Type] Regression, [Type] Security, [Type] WP Core Ticket, Backport from WordPress Core, Gutenberg Plugin, New Block.
• Labels found: .

Read more about Type labels in Gutenberg. Don't worry if you don't have the required permissions to add labels; the PR reviewer should be able to help with the task.

[github-actions]

The following accounts have interacted with this PR and/or linked issues. I will continue to update these lists as activity occurs. You can also manually ask me to refresh this list by adding the props-bot label.

If you're merging code through a pull request on GitHub, copy and paste the following into the bottom of the merge commit message.

Co-authored-by: nani-samireddy <nanisamireddy@git.wordpress.org>
Co-authored-by: Mamaduka <mamaduka@git.wordpress.org>
Co-authored-by: t-hamano <wildworks@git.wordpress.org>

To understand the WordPress project's expectations around crediting contributors, please review the Contributor Attribution page in the Core Handbook.

[Mamaduka]

Thanks, @nani-samireddy!