net: TestLookupHostCancel failures with `i/o timeout` or temporary error

[gopherbot]

#!watchflakes
post <- pkg == "net" && test == "TestLookupHostCancel" && (
	`i/o timeout` ||
	`This is usually a temporary error during hostname resolution and means that the local server did not receive a response from an authoritative server.`)

Issue created automatically to collect these failures.

Example (log):

--- FAIL: TestLookupHostCancel (16.33s)
    lookup_test.go:1007: lookup www.google.com on 8.8.8.8:53: read udp 192.168.64.101:49520->8.8.8.8:53: i/o timeout

Another example (log):

=== RUN   TestLookupHostCancel
=== PAUSE TestLookupHostCancel
=== CONT  TestLookupHostCancel
    lookup_test.go:986: lookup www.google.com: getaddrinfow: This is usually a temporary error during hostname resolution and means that the local server did not receive a response from an authoritative server.
--- FAIL: TestLookupHostCancel (0.00s)

— watchflakes

[gopherbot]

Found new dashboard test flakes for:

#!watchflakes
post <- pkg == "net" && test == "TestLookupHostCancel"

2022-12-28 22:16 darwin-amd64-nocgo go@c1760296 net.TestLookupHostCancel (log)

--- FAIL: TestLookupHostCancel (16.33s)
    lookup_test.go:1007: lookup www.google.com on 8.8.8.8:53: read udp 192.168.64.101:49520->8.8.8.8:53: i/o timeout

— watchflakes

[cherrymui]

#50191 may be related.

[bcmills]

(attn @ianlancetaylor @neild for net)