[ci] Update dotnet and global tool installs (#1132)

The `performMultiLevelLookup` parameter has been removed from the dotnet
install steps to ensure that we always attempt to install / use a dotnet
in $(Agent.ToolsDirectory). The dotnet install path will also now be
cleaned up when running on macOS.

Global tools will now be uninstalled before installing the new version
to avoid any potential downgrade errors. Installation will also now use
the DotNetCoreCLI@2 task directly.

Author: pjcollins

build/ci/setup-environment.yml

@@ -6,12 +6,18 @@ parameters:
   javaSdkRoot: $(Agent.ToolsDirectory)\jdk11
 
 steps:
-  # before the build starts, make sure the tooling is as expected
+  # before the build starts, make sure the tooling is as expected. Clear the cache on shared agents
+  - script: |
+      dotnet build-server shutdown
+      rm -rf $(Agent.ToolsDirectory)/dotnet
+    displayName: Remove dotnet cache
+    workingDirectory: $(Pipeline.Workspace)
+    condition: eq(variables['Agent.OS'], 'Darwin')
+
   - task: UseDotNet@2
     displayName: 'Use dotnet $(dotnetVersion)'
     inputs:
       version: $(dotnetVersion)
-      performMultiLevelLookup: true
       includePreviewVersions: true
     condition: ne('$(dotnetVersion)', '')
 
@@ -20,13 +26,25 @@ steps:
       displayName: 'Use dotnet $(dotnetNextVersion)'
       inputs:
         version: $(dotnetNextVersion)
-        performMultiLevelLookup: true
         includePreviewVersions: true
-      
+
+  - script: dotnet --info
+    displayName: Display dotnet info
+
   - ${{ each tool in parameters.dotnetTools }}:
     - ${{ each pair in tool }}:
-      - pwsh: dotnet tool update -g ${{ pair.key }} --version ${{ pair.value }}
-        displayName: 'Install tool: ${{ pair.key }}'
+      - powershell: dotnet tool uninstall ${{ pair.key }} -g
+        displayName: 'Uninstall tool: ${{ pair.key }}'
+        ignoreLASTEXITCODE: true
+      - task: DotNetCoreCLI@2
+        displayName: 'Install tool: ${{ pair.key }} ${{ pair.value }}'
+        inputs:
+          command: custom
+          custom: tool
+          arguments: >-
+            update -g ${{ pair.key }} -v:diag
+            --version ${{ pair.value }}
+            --add-source "https://api.nuget.org/v3/index.json"
 
   - ${{ if eq(parameters.runDotnetNextTest, true) }}:
     - pwsh: |