net/smtp: skip TestTLSSClient on all freebsd platforms

This test seems like it needs attention from a TLS and/or FreeBSD
expert. In the meantime, it needs to stop causing noise on the build
dashboard.

For #19229

Change-Id: If7e9e3533ae7cb29006a670c3e9df90512dcf9f2
Reviewed-on: https://go-review.googlesource.com/c/go/+/370137
Trust: Bryan Mills <bcmills@google.com>
Run-TryBot: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Author: Bryan C. Mills

src/net/smtp/smtp_test.go

@@ -948,7 +948,7 @@ QUIT
 `
 
 func TestTLSClient(t *testing.T) {
-	if (runtime.GOOS == "freebsd" && runtime.GOARCH == "amd64") || runtime.GOOS == "js" {
+	if runtime.GOOS == "freebsd" || runtime.GOOS == "js" {
 		testenv.SkipFlaky(t, 19229)
 	}
 	ln := newLocalListener(t)