fix: update linking for samples (#218)

Author: JustinBeckwith

handwritten/firestore/.circleci/config.yml

@@ -78,7 +78,6 @@ jobs:
           command: |-
             mkdir -p /home/node/.npm-global
             npm install
-            npm link
             chmod +x node_modules/@google-cloud/nodejs-repo-tools/bin/tools
           environment:
             NPM_CONFIG_PREFIX: /home/node/.npm-global