Alert component: UI fixes

[vmilan]

Description

Shortcut: https://app.shortcut.com/cartoteam/story/338746/implement-alert-ui-fixes-in-c4r [sc-338746]

Alert was implemented a few months ago as a new piece of the DS, but due to deadlines, we couldn't apply the UI fixes that design team detected in the QA process. This task is to tackle those fixes.

[shortcut-integration[bot]]

This pull request has been linked to Shortcut Story #338746: Implement Alert UI fixes in C4R.

[github-actions[bot]]

Pull Request Test Coverage Report for Build 7329666167

Warning: This coverage report may be inaccurate.

We've detected an issue with your CI configuration that might affect the accuracy of this pull request's coverage report. To ensure accuracy in future PRs, please see these guidelines. A quick fix for this PR: rebase it; your next report should be accurate.

• 0 of 2 (0.0%) changed or added relevant lines in 1 file are covered.
• 8 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.002%) to 69.205%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
packages/react-ui/src/theme/sections/components/feedback.js	0	2	0.0%
<!--	Total:	0	2	0.0%	-->

Files with Coverage Reduction	New Missed Lines	%
packages/react-ui/src/widgets/PieWidgetUI/PieWidgetUI.js	3	56.7%
packages/react-redux/src/slices/cartoSlice.js	5	84.52%
<!--	Total:	8		-->

Totals
Change from base Build 7221318701:	-0.002%
Covered Lines:	2609
Relevant Lines:	3446

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💛 - Coveralls

[github-actions[bot]]

Visit the preview URL for this PR (updated for commit e5cdc9b):

https://cartodb-fb-storybook-react-dev--pr813-feature-alert-ui-8htnkysr.web.app

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