[BUG]: Incorrect HTTP_PROXY variable when using proxy without credentials

[domsew]

What happened?

When agent is configured with --proxyurl http://proxy.example.com:8888 but without --proxyusername and --proxypassword, the ennviroment variable is set to:
HTTP_PROXY="http://undefined:undefined@proxy.example.com:8888/" instead of HTTP_PROXY="http://proxy.example.com:8888/"

Versions

4.248.0 / Linux

Environment type (Please select at least one enviroment where you face this issue)

• Self-Hosted
• Microsoft Hosted
• VMSS Pool
• Container

Azure DevOps Server type

dev.azure.com (formerly visualstudio.com)

Azure DevOps Server Version (if applicable)

No response

Operation system

Debian bookworm

Version controll system

git

Relevant log output