[Enhancement] Update Alert success icon to align with VADS

[TimRoe]

Description of Change

Updated Alert success variant to have CheckCircle icon instead of Check to align with VADS. Updated success unit tests to reflect the checks and pass.

Testing

Checked iOS/Web/Android looked good in light and dark mode.

• [x] Tested on iOS
• [x] Tested on Android
• [x] Tested on Web

PR Checklist

Code reviewer validation:

• General
  • [x] PR is linked to ticket(s)
  • [x] PR has changelog label applied if it's to be included in the changelog
  • [x] Acceptance criteria:
    • All satisfied or
    • Documented reason for not being performed or
    • Split to separate ticket and ticket is linked by relevant AC(s)
  • [x] Above PR sections adequately filled out
  • [x] If any breaking changes, in accordance with the pre-1.0.0 versioning guidelines: a CU ticket has been created for the VA Mobile App detailing necessary adjustments with the package version that will be published by this ticket
• Code
  • [x] Tests are included if appropriate (or split to separate ticket)
  • [x] New functions have proper TSDoc annotations

Publish

If changes warrant a new version per the versioning guidelines and the PR is approved and ready to merge:

• [x] Merge main into branch
• [x] Merge branch to main
• [x] Verify that Check Component Integrations workflow ran successfully
• [x] Publish new version after merging