fix:(track.ts) if environment variables were set, use proxy agent.

[takao-s]

Description

Fixed: If you run firebase login behind the proxy server , you will see "Error: An unexpected error has occurred." in your termial after a few seconds, even if you set the environment variables such as HTTP_PROXY.
Because track.ts try to fetch to the GA4 without proxy settings.

I fixed track.ts to use proxy-agent when the environment variables such as HTTP_PROXY are set.

Scenarios Tested

I manually tested ...

1. firebase login behind the proxy with enviroment variables. -> Success
2. firebase login behind the proxy without enviroment variables. -> Error
3. firebase login directly connected to the Internet with enviroment variables. -> Error
4. firebase login directly connected to the Internet without enviroment variables. -> Success

Sample Commands

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