net: improve GODEBUG=netdns=1 debug messages
Fixes #69680
Change-Id: I73b0506c7a3245ba282cffabe47543f5fce86692
GitHub-Last-Rev:
4c6a1a4c706f39d2756c65b72b78896cd4881302
GitHub-Pull-Request: golang/go#69684
Reviewed-on: https://go-review.googlesource.com/c/go/+/616263
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>