Don't redact ABExp Contact

[lramos15]

Fix #308788

[Copilot]

Pull request overview

This PR fixes telemetry PII-cleaning unintentionally redacting experimentation assignment context (e.g. when assignment strings contain substrings like key/token), which can break experimentation analysis and targeting.

Changes:

• Mark experiment/ABExp assignment context as “trusted” so it bypasses the generic secret redaction logic.
• Update Copilot telemetry plumbing to propagate trusted values through shared properties and sender APIs.
• Tighten internal-event sending behavior for Copilot’s MSFT telemetry sender.

Show a summary per file

File	Description
src/vs/platform/telemetry/common/telemetryService.ts	Wraps experiment properties in TelemetryTrustedValue so PII cleaning won’t redact ABExp context.
extensions/copilot/src/platform/telemetry/common/msftTelemetrySender.ts	Removes a redundant postEvent helper and ensures internal telemetry is gated on internal status.
extensions/copilot/src/platform/telemetry/common/baseTelemetryService.ts	Stores abexp.assignmentcontext as a trusted value and adjusts how experimentation events are forwarded to senders.

Copilot's findings

Comments suppressed due to low confidence (1)

src/vs/platform/telemetry/common/telemetryService.ts:136

• setExperimentProperty now wraps all experiment properties in TelemetryTrustedValue to bypass cleanData redaction. There are existing unit tests for TelemetryService but none that assert experiment properties containing substrings like "token"/"key" are preserved (the motivating regression in #308788). Please add a test (e.g. in src/vs/platform/telemetry/test/browser/telemetryService.test.ts) that sets an experiment property with such a value, logs an event, and verifies the appender receives the unredacted assignment context.

	setExperimentProperty(name: string, value: string): void {
		this._experimentProperties[name] = new TelemetryTrustedValue(value);

		// On first call, flush all pending events that were buffered waiting for experiment properties
		if (!this._isExperimentPropertySet) {
			this._flushPendingEvents();
		}
	}

• Files reviewed: 3/3 changed files
• Comments generated: 1