Fixed Item key unspected change on List component.

[douglasjunior]

First of all, thank you for your contribution! :-)

Please makes sure that these checkboxes are checked before submitting your PR, thank you!

• Make sure that you propose PR to right branch: bugfix for master, feature for branch feature.
• Make sure that you follow antd's code convention.
• Run npm run lint and fix those errors before submitting in order to keep consistent code style.
• Rebase before creating a PR to keep commit history clear.
• Add some descriptions and refer relative issues for you PR.

Extra checklist:

if isBugFix :

• Make sure that you add at least one unit test for the bug which you had fixed.
  Ps: I'm not sure how to add the tests to this case.

This PR fixed the #12298 where this List component is changing the Item key after refresh.

Before	After

[ant-design-bot]

Deploy preview for ant-design ready!

Built with commit 7875ae8

https://deploy-preview-12299--ant-design.netlify.com