fix(rebalancing): honor latest suspension duration

[ReubenBond]

Explicit suspension requests previously retained the later of the existing and requested deadlines. A shorter follow-up request could therefore report a duration greater than the caller requested.

Set the suspension deadline from the latest explicit request and add regression coverage for shortening and extending a suspension.

Fixes #10478

Microsoft Reviewers: Open in CodeFlow

[Copilot]

Pull request overview

This PR updates Orleans’ activation rebalancer suspension logic so that an explicit suspension request overwrites any prior explicit suspension deadline (instead of retaining the later deadline), and adds a regression test to validate shortening/extending behavior.

Changes:

• Change ActivationRebalancerWorker.SuspendFor to set _suspendedUntilTs directly (honor latest explicit request).
• Add a new regression test covering shortening and extending an explicit suspension duration.

Show a summary per file

File	Description
test/Orleans.Placement.Tests/ActivationRebalancingTests/ControlRebalancerTests.cs	Adds a regression test for latest explicit suspension duration semantics.
src/Orleans.Runtime/Placement/Rebalancing/ActivationRebalancerWorker.cs	Updates suspension deadline assignment to reflect the latest explicit request.

Review details

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• Files reviewed: 2/2 changed files
• Comments generated: 1
• Review effort level: Lite

[Copilot]

Review details

Suppressed comments (1)

Previously missed (1) — in code that hasn't changed since the last review.

test/Orleans.Placement.Tests/ActivationRebalancingTests/ControlRebalancerTests.cs:127

• The test does not currently verify that the first (longer) suspension request actually took effect. If the initial call were ignored (or clamped), the rest of the test could still pass because it only asserts on the subsequent shorter/longer follow-up requests. Adding assertions on afterLongerCall makes the regression coverage stronger and ensures the scenario setup is valid.

        await rebalancer.SuspendRebalancing(longerDuration);
        var afterLongerCall = await rebalancer.GetRebalancingReport();

• Files reviewed: 2/2 changed files
• Comments generated: 0 new
• Review effort level: Lite