Remove invalid tests

PackageMigratorIntegrationTests no longer works because we no longer
have a valid registry to migrate to.

Author: chkuang-g

build.gradle

@@ -1950,23 +1950,6 @@ createUnityIntegrationTest(
    new File("Google.PackageManagerClientIntegrationTests.dll.mdb")],
   null, [])
 
-createUnityIntegrationTest(
-  "testPackageMigratorIntegrationTests",
-  ("Imports the plugin into a Unity project and uses the Package Migrator " +
-   "list packages that can be migrated and self migrate EDM to UPM. "),
-  [compilePackageManagerResolver],
-  "PackageMigratorIntegrationTests",
-  fileTree(new File(new File(new File(project.ext.pluginSourceDir,
-                             "PackageManagerResolver"), "test"),
-                    "PackageMigratorIntegrationTests")),
-  [new File("Google.PackageMigratorIntegrationTests.dll"),
-   new File("Google.PackageMigratorIntegrationTests.dll.mdb")],
-  new File(
-    project.ext.scriptDirectory,
-    "source/PackageManagerResolver/test/" +
-    "PackageMigratorIntegrationTestsUnityProject"),
-  [])
-
 task cleanTests(type: Delete) {
   description "Clean test directories."
   delete project.ext.testDir