fix(analytics-browser): cookie re-entrancy problem in isEnabled

[daniel-graham-amplitude]

Summary

Change "CookieStorage" isEnabled function to set "testValue" as a local variable instead of a static variable, which can cause re-entrancy issues.

Checklist

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• Does your PR have a breaking change?: No

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Note

Low Risk
Small, isolated change to cookie availability probing plus added tests; low risk aside from subtle behavior differences under concurrent calls.

Overview
Fixes a re-entrancy/race issue in CookieStorage.isEnabled() by removing the shared static testValue and using a per-call local value when writing/reading the temporary probe cookie.

Adds a Jest regression test that runs isEnabled() concurrently across instances, and includes a simple test-server HTML page to manually verify parallel and sequential isEnabled() calls stay consistently true.

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[Copilot]

Pull request overview

This PR fixes a re-entrancy bug in the CookieStorage.isEnabled() method where concurrent calls from multiple instances could interfere with each other due to a shared static variable. The fix changes testValue from a static class variable to a local variable within the method.

Changes:

• Removed static testValue variable and made it local to isEnabled() method to prevent concurrent calls from different instances from interfering with each other
• Added regression test to verify concurrent calls to isEnabled() work correctly
• Added manual test HTML file to verify the fix in a browser environment

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
packages/analytics-core/src/storage/cookie.ts	Changed testValue from static class variable to local variable in isEnabled() method
packages/analytics-core/test/storage/cookies.test.ts	Added regression test for re-entrancy issue with concurrent isEnabled() calls
test-server/cookies/is-enabled.html	Added manual browser test for verifying parallel and sequential isEnabled() calls

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[Mercy811]

Thanks Dan!! LGTM!