Use --quiet with bundler instead of grep hack

What does this Merge Request do?

This MR changes the experimental 'quiet' mode from piping the output of bundle install .. to | egrep -v '^Using '" to just adding --quiet to bundle install ... With the previous implementation, unfortunately a failed bundle install .. would not pass on its exit code to make and so a gdk install/update would continue despite the obvious error 😬

Closes #1039 (closed)

Merge Request checklist

• Tests added for new functionality. If not, please raise Issue to follow-up.
• This change is backward compatible. If not, please include steps to communicate to our users.
• Documentation added/updated, if needed.
• gdk doctor test added, if needed.