Refactor test servers to make them less global.

test/get/hosted/unlock_if_new_is_unsatisfied_test.dart

Index: test/get/hosted/unlock_if_new_is_unsatisfied_test.dart
diff --git a/test/get/hosted/unlock_if_new_is_unsatisfied_test.dart b/test/get/hosted/unlock_if_new_is_unsatisfied_test.dart
index b824a2e8b265fec30dd6406bc7707c3e472eba8a..fd65adc5202c51dde08c1328331947505ac4aea6 100644
--- a/test/get/hosted/unlock_if_new_is_unsatisfied_test.dart
+++ b/test/get/hosted/unlock_if_new_is_unsatisfied_test.dart
@@ -26,7 +26,7 @@ main() {
       "qux": "1.0.0"
     }).validate();
 
-    servePackages((builder) {
+    globalPackageServer.add((builder) {
       builder.serve("foo", "2.0.0", deps: {"bar": "<3.0.0"});
       builder.serve("bar", "2.0.0", deps: {"baz": "<3.0.0"});
       builder.serve("baz", "2.0.0", deps: {"qux": "<3.0.0"});