crypto/x509: rename duplicated test

Rename the old TestPlatformVerifier to TestPlatformVerifierLegacy, and
add TODO about removing it once the synthetic root is widely deployed on
builders.

Updates #52108

Change-Id: I6cdba268e4738804c7f76ea18c354470b3e0318c
Reviewed-on: https://go-review.googlesource.com/c/go/+/505755
Run-TryBot: Roland Shoemaker <[email protected]>
Auto-Submit: Roland Shoemaker <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: Bryan Mills <[email protected]>

Author: rolandshoemaker

src/crypto/x509/root_darwin_test.go

@@ -12,7 +12,9 @@ import (
 	"time"
 )
 
-func TestPlatformVerifier(t *testing.T) {
+func TestPlatformVerifierLegacy(t *testing.T) {
+	// TODO(#52108): This can be removed once the synthetic test root is deployed on
+	// builders.
 	if !testenv.HasExternalNetwork() {
 		t.Skip()
 	}

src/crypto/x509/root_windows_test.go

@@ -16,7 +16,9 @@ import (
 	"time"
 )
 
-func TestPlatformVerifier(t *testing.T) {
+func TestPlatformVerifierLegacy(t *testing.T) {
+	// TODO(#52108): This can be removed once the synthetic test root is deployed on
+	// builders.
 	if !testenv.HasExternalNetwork() {
 		t.Skip()
 	}