Revert "[build] delete platform-31 folder on test jobs (#6103)" (#6372)

Reverts: #6103

This reverts commit 21751b5.

API-31 is stable and is now expected to be on CI machines in the
final location (`…/platforms/android-31`), not at `…/android-S`.

Author: jpobst

build-tools/automation/azure-pipelines.yaml

@@ -173,8 +173,6 @@ stages:
 
     - template: yaml-templates\clean.yaml
 
-    - template: yaml-templates\delete-platform-31.yaml
-
     - script: |
         echo ##vso[task.setvariable variable=JI_JAVA_HOME]%USERPROFILE%\android-toolchain\$(XA.Jdk11.Folder)
       displayName: set JI_JAVA_HOME
@@ -295,8 +293,6 @@ stages:
 
     - template: yaml-templates\clean.yaml
 
-    - template: yaml-templates\delete-platform-31.yaml
-
     - script: |
         echo ##vso[task.setvariable variable=JI_JAVA_HOME]%USERPROFILE%\android-toolchain\$(XA.Jdk11.Folder)
       displayName: set JI_JAVA_HOME

build-tools/automation/yaml-templates/delete-platform-31.yaml

@@ -19,8 +19,6 @@ steps:
   parameters:
     provisionExtraArgs: ${{ parameters.provisionExtraArgs }}
 
-- template: delete-platform-31.yaml
-
 - script: |
     echo "##vso[task.setvariable variable=JI_JAVA_HOME]$HOME/Library/Android/${{ parameters.jdkTestFolder }}"
     echo "##vso[task.setvariable variable=DOTNET_TOOL_PATH]$HOME/Library/Android/dotnet/dotnet"