Set locale for ubuntu 18.04 (#31649)

Author: John Luo

.azure/pipelines/ci.yml

@@ -701,6 +701,9 @@ stages:
     pool:
       vmImage: 'ubuntu-18.04'
     variables:
+      LC_ALL: 'en_US.UTF-8'
+      LANG: 'en_US.UTF-8'
+      LANGUAGE: 'en_US.UTF-8'
       DotNetCoreSdkDir: $(Agent.ToolsDirectory)/dotnet
       # This isn't needed in the path because build does not need to _use_ global tools.
       DOTNET_CLI_HOME: $(System.DefaultWorkingDirectory)

.azure/pipelines/jobs/default-build.yml

@@ -116,6 +116,10 @@ jobs:
     - DOTNET_CLI_HOME: $(System.DefaultWorkingDirectory)
     - DOTNET_SKIP_FIRST_TIME_EXPERIENCE: true
     - TeamName: AspNetCore
+    - ${{ if eq(parameters.agentOs, 'Linux') }}:
+      - LC_ALL: 'en_US.UTF-8'
+      - LANG: 'en_US.UTF-8'
+      - LANGUAGE: 'en_US.UTF-8'
     - ${{ if and(eq(parameters.installJdk, 'true'), eq(parameters.agentOs, 'Windows')) }}:
       - JAVA_HOME: $(Agent.BuildDirectory)\.tools\jdk\win-x64
     - ${{ if or(ne(parameters.codeSign, true), ne(variables['System.TeamProject'], 'internal')) }}: