remove long-disabled grpc_coverage kokoro job (#29400)

tools/internal_ci/linux/grpc_coverage.cfg

@@ -1,25 +0,0 @@
-# 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: "**/*sponge_log.*"
-    regex: "github/grpc/reports/**"
-  }
-}

tools/internal_ci/linux/grpc_coverage.sh

@@ -1,49 +0,0 @@
-#!/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 $0)/../../..
-
-source tools/internal_ci/helper_scripts/prepare_build_linux_rc
-
-python3 tools/run_tests/run_tests.py \
-   -l c c++ -x coverage_cpp/sponge_log.xml \
-   --use_docker -t -c gcov -j 2 || FAILED="true"
-
-python3 tools/run_tests/run_tests.py \
-   -l python -x coverage_python/sponge_log.xml \
-   --use_docker -t -c gcov -j 2 || FAILED="true"
-
-python3 tools/run_tests/run_tests.py \
-   -l ruby -x coverage_ruby/sponge_log.xml \
-   --use_docker -t -c gcov -j 2 || FAILED="true"
-
-python3 tools/run_tests/run_tests.py \
-   -l php -x coverage_php/sponge_log.xml \
-   --use_docker -t -c gcov -j 2 || FAILED="true"
-  
-# HTML reports can't be easily displayed in GCS, so create a zip archive
-# and put it under reports directory to get it uploaded as an artifact.
-zip -q -r coverage_report.zip reports || true
-rm -rf reports || true
-mkdir reports  || true
-mv coverage_report.zip reports || true
-
-if [ "$FAILED" != "" ]
-then
-  exit 1
-fi