[TX flow] Adjust icon color for dark mode

[usame-algan]

What it solves

Part of #2067

How this PR fixes it

Addresses design feedback

How to test it

1. Open the App
2. Create a new transaction
3. Switch to dark/light mode
4. Compare status widget to design

Screenshots

Checklist

• I've tested the branch on mobile 📱
• I've documented how it affects the analytics (if at all) 📊
• I've written a unit/e2e test for it (if applicable) 🧑‍💻

[github-actions]

Branch preview

✅ Deploy successful!

https://ui_feedback--walletweb.review-wallet-web.5afe.dev

[github-actions]

ESLint Summary View Full Report

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Type	Occurrences	Fixable
Errors	0	0
Warnings	0	0
Ignored	0	N/A

• Result: ✅ success
• Annotations: 0 total

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