Prevent orphaned promises when resolving utility models

[vritant24]

No description provided.

[Copilot]

Pull request overview

This PR updates Copilot language model utility-alias refresh handling to avoid leaving test/background refresh promises pending after disposal.

Changes:

• Wraps utility override refreshes in a Throttler and cancellation-aware waits.
• Adds/updates tests covering teardown and disposal cancellation behavior.

Show a summary per file

File	Description
extensions/copilot/src/extension/conversation/vscode-node/languageModelAccess.ts	Adds throttled, cancellation-aware utility alias override refresh logic.
extensions/copilot/src/extension/conversation/vscode-node/test/languageModelAccess.test.ts	Adds test coverage for cancelled/coalesced background refreshes and cleans up a stalled test promise.

Copilot's findings

• Files reviewed: 2/2 changed files
• Comments generated: 1

[Copilot]

Copilot's findings

Comments suppressed due to low confidence (1)

extensions/copilot/src/extension/conversation/vscode-node/test/languageModelAccess.test.ts:341

• firstRefresh is a Promise<void>, so a successful raceTimeout(firstRefresh, ...) also returns undefined. This makes the success assertion fail even when cancellation worked; race a promise that resolves to an explicit truthy sentinel instead.

			const settledFirstRefresh = await raceTimeout(firstRefresh, 2_000);
			assert.ok(settledFirstRefresh, 'expected the superseded stalled refresh to resolve after cancellation');

• Files reviewed: 2/2 changed files
• Comments generated: 2