Temporarily re-enable .NET 5 SDK install step (Azure#18298)

Author: weshaggard

eng/pipelines/templates/steps/install-dotnet.yml

@@ -1,15 +1,15 @@
 # All required SDKs/runtimes are available on DevOps agents
-steps: []
+#steps: []
 # Installation steps need to be uncommented when switching to a newer SDK that's not available on DevOps agents
-#steps:
-#  - task: UseDotNet@2
-#    displayName: 'Use .NET Core SDK'
-#    inputs:
-#      useGlobalJson: true
-#      performMultiLevelLookup: true
-#  - task: UseDotNet@2
-#    condition: ne(variables['Agent.OS'], 'Windows_NT') # Windows supports MultiLevelLookup and doesn't need explicit framework installation
-#    displayName: 'Use .NET Core 2.1 runtime'
-#    inputs:
-#      packageType: runtime
-#      version: "2.1.x"
+steps:
+ - task: UseDotNet@2
+   displayName: 'Use .NET Core SDK'
+   inputs:
+     useGlobalJson: true
+     performMultiLevelLookup: true
+ - task: UseDotNet@2
+   condition: ne(variables['Agent.OS'], 'Windows_NT') # Windows supports MultiLevelLookup and doesn't need explicit framework installation
+   displayName: 'Use .NET Core 2.1 runtime'
+   inputs:
+     packageType: runtime
+     version: "2.1.x"