extensions: keep update checks on polling cadence

[Jimmy Lewis (jimmylewis)]

Do not reschedule the full installed-extension update check when an extension's auto-update delay expires. Clarify that delay expiry makes an update eligible rather than guaranteeing its installation time.

Addresses #339362 by keeping the UTD check cadence regular, not rescheduling to align immediately when an extension exits quarantine.

Prior to that PR, the maximum delay for an auto-update was max(Cadence). With that change and the alignment of 12-hr quarantine and 12-hr cadence, the maximum became max(Quarantine) - which would always be less than 2*max(Cadence). The changes in this PR can cause the maximum delay between publish and auto-update to increase to max(Quarantine+Cadence), which could be as much as double, but maintains both the quarantine and the distributed rollout.

Co-authored-by: Copilot 223556219+Copilot@users.noreply.github.com

[Copilot]

Copilot review overview

🟡 Changes recommended

The tooltip still incorrectly guarantees an update at the quarantine delay.

Review effort: Balanced
Findings: 1

Open (1)

• Clarify tooltip timing to reflect eligibility threshold · New

What changed in this PR

Keeps extension update checks on their regular cadence instead of rescheduling when quarantine expires.

Changes:

• Removes quarantine-expiry update-check scheduling.
• Adds regression coverage for polling cadence.
• Updates delayed-update messaging.

File	Description
extensionsWorkbenchService.ts	Removes expiry-triggered checks.
extensionsWorkbenchService.test.ts	Tests cadence preservation.
extensionsActions.ts	Revises eligibility messaging.

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[Sandeep Somavarapu (sandy081)]

This makes sense to me. Keeping the regular polling cadence avoids synchronizing Marketplace requests, with the understood tradeoff that updates can take up to one additional polling interval. I’ll take over this PR and get it ready.