Block Editor: Remove truncation from media tab preview tooltips

[Sukhendu2002]

What?

Closes: #69729

This PR removes the 25-character truncation from block-inserter media tab item preview tooltips, making them consistent with Pattern previews.

Testing Instructions

• Added media items with long titles to the media library
• Opened the block inserter and navigated to the media tab
• Verified that tooltips now show the complete title without truncation when hovering over media items

Screenshots or screencast

Before	After

[github-actions]

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Co-authored-by: Sukhendu2002 <sukhendu2002@git.wordpress.org>
Co-authored-by: Mamaduka <mamaduka@git.wordpress.org>
Co-authored-by: t-hamano <wildworks@git.wordpress.org>

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[Sukhendu2002]

Hey @Mamaduka! PR is now ready for review. Feel free to take a look whenever you have some time. Thanks!

[Mamaduka]

Thank you, @Sukhendu2002!

[t-hamano]

I am checking the PRs with the "Backport to WP Minor Release" label applied to clarify which PRs should be backported to the WordPress 6.8.2 release.

This PR doesn't fix the issue that first appeared in 6.8; it's just a small improvement to make the media tooltip text fully visible.

I think it's safe to include it in the 6.8.2 release candidate, but what do you think?

[Mamaduka]

It's a minor fix and a good candidate for 6.8.2.

[t-hamano]

This PR was cherry-picked into the wp/6.8 branch for the WP 6.8.2 release: #70557