Assess if we can avoid putenv usage to avoid some thread safety issues

[ssddanbrown]

In thread error-prone environments (Apache on XAMPP windows by default for example) there can be issues with things like config loading, where config ends up blank.

This can be helped by config caching as a workaround, which we don't advise/document, but I feel it's better to avoid such thread problematic scenarios completely where possible, which it looks like it may be:

laravel/framework#28908
laravel/framework#28740

From what I can tell, this could effect libraries that use putenv/getenv, so might need to think-about/audit potential impacts there.