fix preRelease gulp tasks and location

Author: eleanorjboyd

build/azure-pipeline.pre-release.yml

@@ -91,7 +91,7 @@ extends:
       - script: python ./build/update_package_file.py
         displayName: Update telemetry in package.json
 
-      - script: npm run addExtensionPackDependencies
+      - script: npm run addExtensionPackDependenciesPreRelease
         displayName: Update optional extension dependencies
 
       - script: npx gulp prePublishBundle

package.json

@@ -1671,6 +1671,7 @@
         "format-fix": "prettier --write 'src/**/*.ts' 'build/**/*.js' '.github/**/*.yml' gulpfile.js",
         "clean": "gulp clean",
         "addExtensionPackDependencies": "gulp addExtensionPackDependencies",
+        "addExtensionPackDependenciesPreRelease": "gulp addExtensionPackDependenciesPreRelease",
         "updateBuildNumber": "gulp updateBuildNumber",
         "verifyBundle": "gulp verifyBundle",
         "webpack": "webpack"