chore: [UIE-9913] - IAM: Cleanup iamRbacPrimaryNavChanges feature flag

[abailly-akamai]

Description 📝

This PR removes the much involved iamRbacPrimaryNavChanges which has now been the default for a few months.

It defaults Cloud Manager to use the true value of the flag while keeping the redirects (ie: /account/billing 👉 /billing etc) for backward compatibility. Those redirects could eventually be removed as a secondary cleanup.

This change will change nothing for our users, it justs cleans up obsolete logic for a flag having reached deprecation status.

Changes 🔄

• Remove iamRbacPrimaryNavChanges feature flag logic
• Update e2e tests
• Update unit tests

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 📷

There shouldn't be any functional or visual regression a part of this PR.

How to test 🧪

Verification steps

⚠️ The steps below should be tested with both an IAM enabled account and an IAM without the customer tag (iam_beta)
The steps should be also compared to the current production behavior (no regression)

• Verify Primary Navigation behaves as expected
  • items
  • order
  • destination
• Confirm all profile pages behave as expected
• Confirm redirects (account/<feature> to <feature>

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

🔺 2 failing tests on test run #4 ↗︎

❌ Failing	✅ Passing	↪️ Skipped	🕐 Duration
2 Failing	863 Passing	11 Skipped	42m 59s

Details

Failing Tests
	Spec	Test
❌	timerange-verification.spec.ts	Cloud Manager Cypress Tests→Integration tests for verifying Cloudpulse custom and preset configurations » should implement and validate custom date/time picker for a specific date and time range
❌	clone-linode.spec.ts	Cloud Manager Cypress Tests→clone linode » can clone a Linode from Linode details page

Troubleshooting

Use this command to re-run the failing tests:

pnpm cy:run -s "cypress/e2e/core/cloudpulse/timerange-verification.spec.ts,cypress/e2e/core/linodes/clone-linode.spec.ts"