Update aspnetcore-corert to .NET Core 3.1 (#5436)

* Update aspnetcore-corert to .NET Core 3.1

* Strip unnecessary dependencies

frameworks/CSharp/aspnetcore-corert/aspcore-corert-rhtx.dockerfile

@@ -1,16 +1,11 @@
-FROM mcr.microsoft.com/dotnet/core/sdk:2.2 AS build
-RUN echo "deb http://llvm.org/apt/trusty/ llvm-toolchain-trusty-3.9 main" | tee /etc/apt/sources.list.d/llvm.list
-RUN wget -O - http://llvm.org/apt/llvm-snapshot.gpg.key | apt-key add -
+FROM mcr.microsoft.com/dotnet/core/sdk:3.1 AS build
 RUN apt-get update
-RUN apt-get -yqq install cmake clang-3.9 libicu57 libunwind8 uuid-dev libcurl4-openssl-dev zlib1g-dev libkrb5-dev
-RUN wget https://download.visualstudio.microsoft.com/download/pr/886b4a4c-30af-454b-8bec-81c72b7b4e1f/d1a0c8de9abb36d8535363ede4a15de6/dotnet-sdk-3.0.100-linux-x64.tar.gz
-RUN mkdir -p /dotnet
-RUN tar zxf dotnet-sdk-3.0.100-linux-x64.tar.gz -C /dotnet
+RUN apt-get -yqq install clang zlib1g-dev libkrb5-dev libtinfo5
 WORKDIR /app
 COPY PlatformBenchmarks .
-RUN /dotnet/dotnet publish -c Release -o out -r linux-x64
+RUN dotnet publish -c Release -o out -r linux-x64
 
-FROM mcr.microsoft.com/dotnet/core/aspnet:3.0 AS runtime
+FROM mcr.microsoft.com/dotnet/core/aspnet:3.1 AS runtime
 WORKDIR /app
 COPY --from=build /app/out ./
 

frameworks/CSharp/aspnetcore-corert/aspcore-corert.dockerfile

@@ -1,16 +1,11 @@
-FROM mcr.microsoft.com/dotnet/core/sdk:2.2 AS build
-RUN echo "deb http://llvm.org/apt/trusty/ llvm-toolchain-trusty-3.9 main" | tee /etc/apt/sources.list.d/llvm.list
-RUN wget -O - http://llvm.org/apt/llvm-snapshot.gpg.key | apt-key add -
+FROM mcr.microsoft.com/dotnet/core/sdk:3.1 AS build
 RUN apt-get update
-RUN apt-get -yqq install cmake clang-3.9 libicu57 libunwind8 uuid-dev libcurl4-openssl-dev zlib1g-dev libkrb5-dev
-RUN wget https://download.visualstudio.microsoft.com/download/pr/886b4a4c-30af-454b-8bec-81c72b7b4e1f/d1a0c8de9abb36d8535363ede4a15de6/dotnet-sdk-3.0.100-linux-x64.tar.gz
-RUN mkdir -p /dotnet
-RUN tar zxf dotnet-sdk-3.0.100-linux-x64.tar.gz -C /dotnet
+RUN apt-get -yqq install clang zlib1g-dev libkrb5-dev libtinfo5
 WORKDIR /app
 COPY PlatformBenchmarks .
-RUN /dotnet/dotnet publish -c Release -o out -r linux-x64
+RUN dotnet publish -c Release -o out -r linux-x64
 
-FROM mcr.microsoft.com/dotnet/core/aspnet:3.0 AS runtime
+FROM mcr.microsoft.com/dotnet/core/aspnet:3.1 AS runtime
 WORKDIR /app
 COPY --from=build /app/out ./