Drop Windows exemption for warning about system cert pool
What does this MR do?
Since Go 1.18, the system cert pool works for Windows (https://github.com/golang/go/issues/16736). We no longer need to handle the warning as a special case.
Why was this MR needed?
Just spotted an outdated comment, and cleans up the code a bit.
What's the best way to test this MR?
Run a job on Windows. The system cert pool should be loaded fine.
What are the relevant issue numbers?
Edited by Stan Hu