fix: [PDI-3226] - Only show Maintenance Policy for Linodes that actually have a Maintenance Policy

[bnussman-akamai]

Description 📝

• Adds extra conditional logic to the Linode Details page to ensure the new "Maintenance Policy" value only shows when the Linode actually supports it
• Updates api-v4 types to reflect the API

Scope 🚢

Upon production release, changes in this PR will be visible to:

• All customers
• Some customers (e.g. in Beta or Limited Availability)
• No customers / Not applicable

Preview 📷

Before	After
A maintenance policy is showing even though this Linode does not have one	Now, no maintenance policy will show because the Linode does not have one

How to test 🧪

• Have a Linode on your account that a maintenance_policy of null and does not have Maintenance Policy in the capabilities array
  • I used Chrome's "Override Content" feature to mock this
• Verify the Maintenance Policy section does not show beside the Linode's status

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

[dwiley-akamai]

Verification steps ✅
Code review ✅
LinodeEntityDetail unit test passes locally & in CI ✅

[linode-gh-bot]

Cloud Manager UI test results

🔺 1 failing test on test run #5 ↗︎

❌ Failing	✅ Passing	↪️ Skipped	🕐 Duration
1 Failing	864 Passing	11 Skipped	38m 37s

Details

Failing Tests
	Spec	Test
❌	smoke-linode-landing-table.spec.ts	Cloud Manager Cypress Tests→linode landing checks for non-empty state with restricted user » checks restricted user with read access has no access to create linode and can see existing linodes

Troubleshooting

Use this command to re-run the failing tests:

pnpm cy:run -s "cypress/e2e/core/linodes/smoke-linode-landing-table.spec.ts"

[jdamore-linode]

Not real sure why that Linode landing page test is failing, it seems like the page is loading in summary view unexpectedly in the CI recording. Couldn't reproduce it locally and can't imagine it's caused by this PR's changes, but I'll keep an eye on it