refactor: use global networkObserver in session replay

[daniel-graham-amplitude]

Summary

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[Copilot]

Pull Request Overview

This PR refactors the session replay package to use a global network observer from the analytics-core package instead of a local implementation. The purpose is to consolidate network observation functionality into a shared utility.

• Replaces local NetworkObservers class with global networkObserver from analytics-core
• Updates network event handling to use subscribe/unsubscribe pattern with NetworkEventCallback
• Removes local network observer implementation and associated tests

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
packages/session-replay-browser/src/session-replay.ts	Updates to use global networkObserver with subscribe/unsubscribe pattern
packages/session-replay-browser/src/observers.ts	Completely removed local NetworkObservers implementation
packages/session-replay-browser/test/session-replay.test.ts	Updates tests to mock global networkObserver instead of local implementation
packages/session-replay-browser/test/observers.test.ts	Removes all tests for local NetworkObservers class

Comments suppressed due to low confidence (2)

packages/session-replay-browser/test/session-replay.test.ts:1924

• The test is using Date.now() for both startTime and endTime, which may not properly test time-based functionality. Consider using jest.useFakeTimers() or mocking Date.now() to control the time values in tests.

        startTime: Date.now(),

packages/session-replay-browser/test/session-replay.test.ts:1925

• The test is using Date.now() for both startTime and endTime, which may not properly test time-based functionality. Consider using jest.useFakeTimers() or mocking Date.now() to control the time values in tests.

        endTime: Date.now(),

[promptless]

✅ No documentation updates required.