drop unused workflow (#2192)

.github/workflows/nostackdriver.yaml

@@ -1,37 +0,0 @@
-# Copyright 2020 The Knative 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.
-
-name: Test
-
-on:
-  pull_request:
-    branches: [ 'main', 'master', 'release-*' ]
-
-jobs:
-
-  nostackdriver:
-    name: Unit Tests w/o stackdriver
-    runs-on: ubuntu-latest
-
-    steps:
-      - name: Set up Go 1.15.x
-        uses: actions/setup-go@v2
-        with:
-          go-version: 1.15.x
-
-      - name: Check out code
-        uses: actions/checkout@v2
-
-      - name: Test w/nostackdriver
-        run: go test -tags=nostackdriver -race ./...