Fix misaligned icons in 'Connected sites' modal

[jase-b]

Fixes #19901: Connected sites modal misaligned icons

Replaced <SiteIcon> with <AvatarFavicon> in <ConnectedSitesList>

Before

After

Manual Testing Steps

• Log in to MetaMask.
• Connect the wallet to at least one site (if not already).
• Open the 'Connected sites' modal.
• Observe all listed site icons are centered within their circular container element.

Pre-merge author checklist

• I've clearly explained:
  • What problem this PR is solving
  • How this problem was solved
  • How reviewers can test my changes
• Sufficient automated test coverage has been added

Pre-merge reviewer checklist

• Manual testing (e.g. pull and build branch, run in browser, test code being changed)
• PR is linked to the appropriate GitHub issue
• IF this PR fixes a bug in the release milestone, add this PR to the release milestone

[github-actions]

CLA Signature Action: All authors have signed the CLA. You may need to manually re-run the blocking PR check if it doesn't pass in a few minutes.

[jase-b]

I have read the CLA Document and I hereby sign the CLA

[codecov]

Codecov Report

Merging #19944 (20a9a62) into develop (c206200) will decrease coverage by 0.01%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop   #19944      +/-   ##
===========================================
- Coverage    69.47%   69.46%   -0.01%     
===========================================
  Files          987      987              
  Lines        37270    37270              
  Branches      9979     9979              
===========================================
- Hits         25890    25888       -2     
- Misses       11380    11382       +2     

Impacted Files	Coverage Δ
...ected-sites-list/connected-sites-list.component.js	46.15% <ø> (ø)

... and 2 files with indirect coverage changes

[NidhiKJha]

The changes look really great. I have suggested some changes to use border color and size from design-system constants. Thanks for your contribution @jase-b

[NidhiKJha]

LGTM! Thanks for your contribution

[jase-b]

LGTM! Thanks for your contribution

Happy to help and more to come 🤝

[vthomas13]

Congrats @jase-b! Really appreciate the contribution 😁