updates for grpc-performance-kokoro-v3 image

tools/gce/create_linux_kokoro_performance_worker_from_image.sh

@@ -22,7 +22,7 @@ cd "$(dirname "$0")"
 
 CLOUD_PROJECT=grpc-testing
 ZONE=us-central1-b  # this zone allows 32core machines
-LATEST_PERF_WORKER_IMAGE=grpc-performance-kokoro-v2  # update if newer image exists
+LATEST_PERF_WORKER_IMAGE=grpc-performance-kokoro-v3  # update if newer image exists
 
 INSTANCE_NAME="${1:-grpc-kokoro-performance-server}"
 MACHINE_TYPE="${2:-n1-standard-32}"

tools/gce/linux_kokoro_performance_worker_init.sh

@@ -133,6 +133,12 @@ sudo cp -r dotnet105_download/shared/Microsoft.NETCore.App/1.0.5/ /usr/share/dot
 wget -q http://security.ubuntu.com/ubuntu/pool/main/i/icu/libicu55_55.1-7ubuntu0.4_amd64.deb
 sudo dpkg -i libicu55_55.1-7ubuntu0.4_amd64.deb
 
+# Install .NET Core 1.1.10 runtime (required to run netcoreapp1.1)
+wget -q -O dotnet_old.tar.gz https://download.visualstudio.microsoft.com/download/pr/b25b5650-0cb8-4699-a347-48d73650da0b/920966211e9bb1907232bbda1faa895a/dotnet-ubuntu.18.04-x64.1.1.10.tar.gz
+mkdir -p dotnet_old
+tar zxf dotnet_old.tar.gz -C dotnet_old
+sudo cp -r dotnet_old/shared/Microsoft.NETCore.App/1.1.10/ /usr/share/dotnet/shared/Microsoft.NETCore.App/
+
 # Ruby dependencies
 gpg --keyserver hkp://keys.gnupg.net --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3
 curl -sSL https://get.rvm.io | bash -s stable --ruby