Revert "Try possible fix for broken GitHub package tests"

This reverts commit 3046f689be.

script/vsts/macos.yml

@@ -27,13 +27,11 @@ phases:
     displayName: Run linter
 
   - script: |
-      # Set up a temporary keychain to enable GitHub package tests
-      security create-keychain -p "" temporary
-      security default-keychain -s temporary
       osascript -e 'tell application "System Events" to keystroke "x"' # clear screen saver
       caffeinate -s script/test # Run with caffeinate to prevent screen saver
     env:
       CI: true
+      CI_PROVIDER: VSTS
     displayName: Run tests
 
   # This step is necessary in the short term due to a bug in the *NIX