Empty proxy for scoped section not respected when proxy is set for unscoped

[AThomsen]

In gitconfig a default proxy is set and an exemption is made for a local server:

[http]
	proxy = http://:@<enterprise-proxy>
[http "https://<git-server-on-lan>"]
	proxy = 

This works in git but not in GCMC.

The error is in:
https://github.com/microsoft/Git-Credential-Manager-Core/blob/540a39816534e6481eaea35fe706eaa7eeb45fd8/src/shared/Microsoft.Git.CredentialManager/Settings.cs#L431-L445

GetSettingValues returns ["", "http://:@<enterprise-proxy>"].

The first value is empty, so Uri.TryCreate returns false, and thus the next value is used.

A workaround is to set NO_PROXY.