Disable alternate diff drivers in setup script (#10378)

bin/install-node-nvm.sh

@@ -73,7 +73,7 @@ npm install
 npm install npm -g
 
 # There was a bug in NPM that caused changes in package-lock.json. Handle that.
-if [ "$TRAVIS" != "true" ] && ! git diff --exit-code package-lock.json >/dev/null; then
+if [ "$TRAVIS" != "true" ] && ! git diff --no-ext-diff --exit-code package-lock.json >/dev/null; then
  if ask "$(warning_message "Your package-lock.json changed, which may mean there's an issue with your NPM cache. Would you like to try and automatically clean it up?" )" N 10; then
  rm -rf node_modules/
  npm cache clean --force >/dev/null 2>&1
@@ -83,7 +83,7 @@ if [ "$TRAVIS" != "true" ] && ! git diff --exit-code package-lock.json >/dev/nul
  npm install
 
  # Check that it's cleaned up now.
- if git diff --exit-code package-lock.json >/dev/null; then
+ if git diff --no-ext-diff --exit-code package-lock.json >/dev/null; then
  echo -e $(warning_message "Confirmed that the NPM cache is cleaned up." )
  else
  echo -e $(error_message "We were unable to clean the NPM cache, please manually review the changes to package-lock.json. Continuing with the setup process..." )