upcoming: [M3-10708] - Display maintenance type and config in linode_migrate event messages

[jaalah-akamai]

Re-opening: #13084

Description 📝

This PR enhances linode_migrate event messages to display maintenance type (emergency/scheduled) and config information when available. Previously, migration events only showed "Linode linode-1 is being migrated" without context about the maintenance type or which config was being used.

Changes 🔄

The changes ensure that:

• Event messages clearly indicate whether a migration is for emergency or scheduled maintenance
• Config information is displayed when a secondary_entity is present in the event
• Messages gracefully handle missing description fields by defaulting to "maintenance"
• All event statuses (failed, finished, scheduled, started) consistently include this information
• Upcoming Table: The start date column now uses the when field as opposed to the start_time which are essentially the same.

Additionally, this PR includes bug fixes for null handling in maintenance-related components and improvements to dev tools for testing these scenarios.

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

Target release date 🗓️

December 2nd

Preview 📷

Before:

• "Linode linode-1 is being migrated."

After:

• "Linode linode-1 is being migrated for emergency maintenance."
• "Linode linode-1 is being migrated for emergency maintenance with config My Debian 11 Disk."
• "Linode linode-1 is being migrated for scheduled maintenance."

Before	After
Linode linode-1 is being migrated.	Linode linode-1 is being migrated for emergency maintenance with config My Debian 11 Disk.

recording.mov

How to test 🧪

Prerequisites

• Enable the vmHostMaintenance feature flag
• Have access to dev tools for mocking events and maintenance records
• "Enable MSW" with Base Preset "Static Mocking"
• Presets > Enable Events: Custom Events
• Presets > Enable Events: Custom Events

Reproduction steps

1. Navigate to Account > Maintenance page
2. Ensure there are maintenance records with status "in_progress" or "started"
3. Create matching events using dev tools with:
   • Select any/all "Linode Migration" from templates
   • For maintenance presets, you can do the same "In Progress - Emergency or Scheduled Migration"

Verification steps

• Verify event messages display "for emergency maintenance" when description: 'emergency'
• Verify event messages display "for scheduled maintenance" when description: 'scheduled'
• Verify event messages display "for maintenance" when description is missing or null
• Verify config information appears when secondary_entity is present: "with config [config name]"
• Verify config information does not appear when secondary_entity is null
• Verify all event statuses (failed, finished, scheduled, started) display correctly
• Verify maintenance type is displayed in bold text
• Test clearing secondary_entity field in dev tools and verify it saves as null
• Verify no runtime errors occur when reason field is null in maintenance records

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

🎉 867 passing tests on test run #4 ↗︎

❌ Failing	✅ Passing	↪️ Skipped	🕐 Duration
0 Failing	867 Passing	11 Skipped	42m 33s