[Fit & Finish] Add width for recent alerts card

[Hailong-am]

Description

Add width for recent alerts card, the default value is 12 which is 1/4 of whole row.

After remove what's new there only have 3 cards left, so the width comes to 16

Issues Resolved

[List any issues this PR will resolve]

Check List

• [ ] New functionality includes testing.
  • [ ] All tests pass
• [ ] New functionality has been documented.
  • [ ] New functionality has javadoc added
• [ ] Commits are signed per the DCO using --signoff

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[Hailong-am]

@amsiglan @riysaxen-amzn @AWSHurneyt can you help to review this PR and add backport 2.x label?