Refactor test servers to make them less global.

test/get/hosted/cached_pubspec_test.dart

Index: test/get/hosted/cached_pubspec_test.dart
diff --git a/test/get/hosted/cached_pubspec_test.dart b/test/get/hosted/cached_pubspec_test.dart
index 8899d1fbaa03cb37923a3445e090820d00d5ad84..7d3cf086fedc8a47341f8f4f43406d4f3fe412e7 100644
--- a/test/get/hosted/cached_pubspec_test.dart
+++ b/test/get/hosted/cached_pubspec_test.dart
@@ -18,7 +18,7 @@ main() {
 
     // Clear the cache. We don't care about anything that was served during
     // the initial get.
-    getRequestedPaths();
+    globalServer.clearRequestedPaths();
 
     d.cacheDir({"foo": "1.2.3"}).validate();
     d.packagesDir({"foo": "1.2.3"}).validate();
@@ -27,7 +27,7 @@ main() {
     pubGet();
 
     // The get should not have requested the pubspec since it's local already.
-    getRequestedPaths().then((paths) {
+    globalServer.requestedPaths.then((paths) {
       expect(paths, isNot(contains("packages/foo/versions/1.2.3.yaml")));
     });
   });