⚡️ Use native fetch to avoid Zone.js change detection in Angular apps

[sdjayna]

Summary

Apply getZoneJsOriginalValue() to fetch() calls in httpRequest.ts, consistent with how timers and event listeners already bypass Zone.js in timer.ts and addEventListener.ts.

Motivation

In Angular applications, Zone.js patches fetch() to trigger change detection. Each Datadog beacon currently triggers a full Angular change detection cycle (~5ms), even though telemetry data never affects the UI.

Measured impact:

• ~85 Datadog requests per 30-second active session (~2.7/sec)
• ~5,000 requests per 30-minute session
• Each request triggers unnecessary Angular change detection
• ~25 seconds of avoidable main thread work per 30-minute session

Changes

• Import getZoneJsOriginalValue and getGlobalObject in httpRequest.ts
• Add getNativeFetch() helper function
• Use native fetch in fetchStrategy() and fetchKeepAliveStrategy()
• Add unit tests verifying Zone.js bypass

Testing

• ✅ All 3127 unit tests pass
• ✅ Type check passes
• ✅ Lint passes
• Added 2 new tests specifically for Zone.js bypass behavior

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[sdjayna]

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