test: test-os win32 adhere standard tmp resolution

The test is making the wrong assumptions about the
value of os.tmpdir() on Windows
test: test-os fix win32 localhost assumption

The test is expecting an invalid result for the loopback
interface network mask, but this issue was fixed in
libuv commit 1d5c61a8b31257733c41fb507762d3eb56eecb2d

Closes #5262 #6673