Rename experimental benchmark job from "..._v2" to "..._gke_experimental" (#27869)

* make it obvious which gke benchmark script is experimental

* add cfg file for new kokoro jobs with a more fitting name

* update performance readme after renaming _v2 benchmark job

* fix typo

tools/internal_ci/linux/grpc_e2e_performance_gke_experiment.cfg

@@ -0,0 +1,25 @@
+# Copyright 2021 The 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_e2e_performance_gke_experiment.sh"
+timeout_mins: 720
+action {
+  define_artifacts {
+    regex: "**/*sponge_log.*"
+    regex: "**/github/grpc/runner/**"
+  }
+}

tools/internal_ci/linux/grpc_e2e_performance_v2.cfg

@@ -15,7 +15,7 @@
 # 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_e2e_performance_v2.sh"
+build_file: "grpc/tools/internal_ci/linux/grpc_e2e_performance_gke_experiment.sh"
 timeout_mins: 720
 action {
   define_artifacts {

tools/run_tests/performance/README.md

@@ -16,7 +16,7 @@ repository, [grpc/test-infra].
 
 These scripts, together with tools defined in [grpc/test-infra], are used in the
 continuous integration setup defined in [grpc_e2e_performance_gke.sh] and
-[grpc_e2e_performance_v2.sh].
+[grpc_e2e_performance_gke_experiment.sh].
 
 #### Generating scenarios
 
@@ -299,11 +299,11 @@ For more information, see the
 in [grpc/test-infra].
 
 For usage examples, see the continuous integration setup defined in
-[grpc_e2e_performance_gke.sh] and [grpc_e2e_performance_v2.sh].
+[grpc_e2e_performance_gke.sh] and [grpc_e2e_performance_gke_experiment.sh].
 
 [grpc/test-infra]: https://github.com/grpc/test-infra
 [grpc_e2e_performance_gke.sh]: ../../internal_ci/linux/grpc_e2e_performance_gke.sh
-[grpc_e2e_performance_v2.sh]: ../../internal_ci/linux/grpc_e2e_performance_v2.sh
+[grpc_e2e_performance_gke_experiment.sh]: ../../internal_ci/linux/grpc_e2e_performance_gke_experiment.sh
 
 ## Approach 2: Running benchmarks locally via legacy tooling (still useful sometimes)