Fix contrib installation when postgres is already installed

When doing a local installation, we can't just check for the database presence,
since we need postgresql-contrib to create the schema

This will at least try to run the AptPackageInstaller again to install the
missing contrib package if it's missing.

Change-Id: I766c39f3e0bfb88eab776050a9e97fcee3bcb5ea
(cherry picked from commit 23b05ba2f9aac1c65987bde30b3397ff2e475860)