net: TestUDPServer failure on windows-amd64-2016

[bcmills]

--- FAIL: TestUDPServer (0.00s)
    server_test.go:255: skipping udp :0<-127.0.0.1 test
    server_test.go:255: skipping udp 0.0.0.0:0<-127.0.0.1 test
    server_test.go:255: skipping udp [::ffff:0.0.0.0]:0<-127.0.0.1 test
    server_test.go:255: skipping udp [::]:0<-::1 test
    server_test.go:255: skipping udp :0<-::1 test
    server_test.go:255: skipping udp 0.0.0.0:0<-::1 test
    server_test.go:255: skipping udp [::ffff:0.0.0.0]:0<-::1 test
    server_test.go:255: skipping udp [::]:0<-127.0.0.1 test
    server_test.go:255: skipping udp :0<-127.0.0.1 test
    server_test.go:255: skipping udp 0.0.0.0:0<-127.0.0.1 test
    server_test.go:255: skipping udp [::ffff:0.0.0.0]:0<-127.0.0.1 test
    server_test.go:255: skipping udp [::]:0<-::1 test
    server_test.go:255: skipping udp :0<-::1 test
    server_test.go:255: skipping udp 0.0.0.0:0<-::1 test
    server_test.go:255: skipping udp [::ffff:0.0.0.0]:0<-::1 test
    server_test.go:255: skipping udp [::]:0<-127.0.0.1 test
    server_test.go:308: #17: read 0; want 15
    server_test.go:255: skipping udp4 :0<-127.0.0.1 test
    server_test.go:255: skipping udp4 0.0.0.0:0<-127.0.0.1 test
    server_test.go:255: skipping udp4 [::ffff:0.0.0.0]:0<-127.0.0.1 test
    server_test.go:255: skipping udp6 :0<-::1 test
    server_test.go:255: skipping udp6 [::]:0<-::1 test
FAIL
FAIL	net	26.769s

Probably a good place to start would be to bring the test logs in line with https://go.dev/wiki/CodeReviewComments#useful-test-failures. 😅

greplogs -l -e 'FAIL: TestUDPServer' --since=2022-08-11
2022-08-11T20:16:37-502b605/windows-amd64-2016

(CC @ianlancetaylor @neild @golang/windows)