Add coverage test to Kokoro

tools/internal_ci/linux/grpc_coverage.cfg

@@ -0,0 +1,24 @@
+# Copyright 2017 gRPC 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.
+
+# Config file for the internal CI (in protobuf text format)
+
+# Location of the continuous shell script in repository.
+build_file: "grpc/tools/internal_ci/linux/grpc_coverage.sh"
+timeout_mins: 420
+action {
+  define_artifacts {
+    regex: "github/grpc/reports/**"
+  }
+}

tools/internal_ci/linux/grpc_coverage.sh

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+#!/usr/bin/env bash
+# Copyright 2017 gRPC 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.
+
+set -ex
+
+# Enter the gRPC repo root
+cd $(dirname $0)/../../..
+
+source tools/internal_ci/helper_scripts/prepare_build_linux_rc
+
+python tools/run_tests/run_tests.py \
+  --use_docker				        \
+  -t                                \
+  -l all                            \
+  -c gcov                           \
+  -x report.xml                     \
+  -j 16
+