fix: [VMP-2536] - Maintenance date from local to utc

[jaalah-akamai]

Description

Fixes incorrect maintenance time display in the Upcoming maintenance table. The code was incorrectly adding notification_period_sec to the when field to derive the start time. The when and start_time fields are equivalent timestamps representing when maintenance occurs, so when should be used directly.

Also improves time display accuracy by rounding up hours when minutes >= 30 (e.g., "1 day 3 hours 49 minutes" displays as "in 1 day 4 hours" instead of "in 1 day 3 hours").

Changes

• Use when directly as the start time instead of adding notification_period_sec
• Remove policies parameter dependency from deriveMaintenanceStartISO and getUpcomingRelativeLabel
• Remove policies query from MaintenanceTableRow component
• Round up hours when minutes >= 30 for better accuracy in day+hour displays
• Update comments to clarify that when and start_time are equivalent timestamps
• Ensure consistent UTC-based time calculations

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

TBD

Preview

Before	After
Shows incorrect time, is was adding notification_period_sec when the field already accounts for this	Shows correct time based on when timestamp

How to test

Prerequisites

• Access to an account with scheduled maintenance events
  • Use Use your devcloud cx account
• Maintenance events with when timestamps and start_time: null

Reproduction steps

1. Navigate to Account → Maintenance → Upcoming tab
2. Observe the "When" column showing relative time until maintenance
3. Compare this branch vs devcloud

Verification steps

• Verify the relative time matches the when timestamp (not when + notification_period_sec)
• Verify times display correctly for events with start_time: null
• Verify times display correctly for events with start_time populated
• Verify rounding works correctly (e.g., "1 day 3 hours 49 minutes" shows as "in 1 day 4 hours")
• Verify no flash/loading state issues when the table first renders

[jaalah-akamai]

Checking with team as to if we need to hotfix this to staging or have it go out in next release via develop branch.

[linode-gh-bot]

Cloud Manager UI test results

🔺 5 failing tests on test run #6 ↗︎

❌ Failing	✅ Passing	↪️ Skipped	🕐 Duration
5 Failing	848 Passing	11 Skipped	60m 9s

Details

Failing Tests
	Spec	Test
❌	create-stackscripts.spec.ts	Cloud Manager Cypress Tests→Create stackscripts » creates a StackScript and deploys a Linode with it
❌	resize-linode.spec.ts	Cloud Manager Cypress Tests→resize linode » resizes a linode by decreasing size
❌	update-stackscripts.spec.ts	Cloud Manager Cypress Tests→Update stackscripts » updates a StackScript
❌	linode-storage.spec.ts	Cloud Manager Cypress Tests→linode storage tab » resize disk
❌	switch-linode-state.spec.ts	Cloud Manager Cypress Tests→switch linode state » powers off a linode from details page

Troubleshooting

Use this command to re-run the failing tests:

pnpm cy:run -s "cypress/e2e/core/stackscripts/create-stackscripts.spec.ts,cypress/e2e/core/linodes/resize-linode.spec.ts,cypress/e2e/core/stackscripts/update-stackscripts.spec.ts,cypress/e2e/core/linodes/linode-storage.spec.ts,cypress/e2e/core/linodes/switch-linode-state.spec.ts"