(MODULES-4682) Pass default_connect_settings to validate service

If using CentOS or RedHat Enterprise Linux with PostgreSQL from
SoftwareCollections the validation of the service fails because
it needs the LD_LIBRARY_PATH environment variable to work properly.

To pass the env for example for postgresql_psql one can only set

class {'postgresql::globals':
  default_connect_settings => {
    'LD_LIBRARY_PATH' => '/opt/rh/rh-postgresql95/root/usr/lib64',
}

This patch passes the default_connect_settings to the
validate_db_connection resource in postgresql::service