fix: [M3-10393] - Add border to countries with white backgrounds

[jaalah-akamai]

Description 📝

This PR modifies the Flag component to conditionally apply CSS borders only to specific countries that require visual distinction. At one time, all flags had borders applied by default, but now borders are only shown for countries that need them for better visual clarity.

Changes 🔄

• Added a list of 3 countries corresponding to our DCs that need borders, using country codes as outlined by UX

Target release date 🗓️

N/A

Preview 📷

Before	After

How to test 🧪

Verification steps

• Go to create linodes
• Open region selector
• Observe these 3 flags have borders

Author Checklists

As an Author, to speed up the review process, I considered 🤔

👀 Doing a self review
❔ Our contribution guidelines
🤏 Splitting feature into small PRs
➕ Adding a changeset
🧪 Providing/improving test coverage
🔐 Removing all sensitive information from the code and PR description
🚩 Using a feature flag to protect the release
👣 Providing comprehensive reproduction steps
📑 Providing or updating our documentation
🕛 Scheduling a pair reviewing session
📱 Providing mobile support
♿ Providing accessibility support

• I have read and considered all applicable items listed above.

As an Author, before moving this PR from Draft to Open, I confirmed ✅

• All tests and CI checks are passing
• TypeScript compilation succeeded without errors
• Code passes all linting rules

[linode-gh-bot]

Cloud Manager UI test results

🔺 5 failing tests on test run #3 ↗︎

❌ Failing	✅ Passing	↪️ Skipped	🕐 Duration
5 Failing	374 Passing	12 Skipped	75m 23s

Details

Failing Tests
	Spec	Test
❌	third-party-access-tokens.spec.ts	Cloud Manager Cypress Tests→Third party access tokens » Third party access tokens
❌	lke-create.spec.ts	Cloud Manager Cypress Tests→LKE Cluster Creation with ACL→with LKE IPACL account capability » LKE Cluster Creation with ACL→with LKE IPACL account capability
❌	lke-create.spec.ts	Cloud Manager Cypress Tests→LKE Cluster Creation with ACL→with LKE IPACL account capability » LKE Cluster Creation with ACL→with LKE IPACL account capability
❌	lke-create.spec.ts	Cloud Manager Cypress Tests→LKE Cluster Creation with ACL→with LKE IPACL account capability » LKE Cluster Creation with ACL→with LKE IPACL account capability
❌	service-transfer.spec.ts	Cloud Manager Cypress Tests→Account service transfers » Account service transfers

Troubleshooting

Use this command to re-run the failing tests:

pnpm cy:run -s "cypress/e2e/core/account/third-party-access-tokens.spec.ts,cypress/e2e/core/kubernetes/lke-create.spec.ts,cypress/e2e/core/account/service-transfer.spec.ts"