Increase timeout for windows portability test (on master) (#27210)

* remove no longer use kokoro job config

* increase timeout of windows grpc_portability job

tools/internal_ci/windows/grpc_portability.cfg

@@ -16,7 +16,7 @@
 
 # Location of the continuous shell script in repository.
 build_file: "grpc/tools/internal_ci/windows/grpc_run_tests_matrix.bat"
-timeout_mins: 240
+timeout_mins: 300
 action {
   define_artifacts {
     regex: "**/*sponge_log.*"

tools/internal_ci/windows/pull_request/grpc_portability.cfg

@@ -1,30 +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/windows/grpc_run_tests_matrix.bat"
-timeout_mins: 240
-action {
-  define_artifacts {
-    regex: "**/*sponge_log.*"
-    regex: "github/grpc/reports/**"
-  }
-}
-
-env_vars {
-  key: "RUN_TESTS_FLAGS"
-  value: "-f portability windows -j 1 --inner_jobs 8 --internal_ci"
-}