Migrate sig-auth e2e tests.

**What this PR does / why we need it:** This PR adds [sig-auth] prefix to
workload e2e tests in accord to requirements of adding a SIG dashboard
to testgrid. Refer PR #48781 for guidelines.

test/e2e/auth/framework.go

@@ -0,0 +1,23 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package auth
+
+import "github.com/onsi/ginkgo"
+
+func SIGDescribe(text string, body func()) bool {
+	return ginkgo.Describe("[sig-auth] "+text, body)
+}