ci: remove unnecessary environment variable (microsoft#2445)

## Summary:

This was unnecessary. Thanks @tido64 for pointing it out.

## Test Plan:

CI should pass

Author: Saadnajmi

.ado/templates/npm-publish-steps.yml

@@ -42,7 +42,5 @@ steps:
 
   - script: |
       rm -f ~/.npmrc
-    env:
-      NODE_AUTH_TOKEN: $(npmAuthToken)
     displayName: Remove npmrc if it exists
     condition: always()