(MODULES-8352) Don't use empty encoding string on initdb
(MODULES-8352) Don't use empty encoding string on initdb

pgsql 11 no longer allows initdb with an empty encoding string. Only
include the string when $encoding is set.

DavidS/puppetlabs-postgresql,puppetlabs/puppetlabs-postgresql,puppetlabs/puppetlabs-postgresql,npwalker/puppetlabs-postgresql,buzzdeee/puppetlabs-postgresql,DavidS/puppetlabs-postgresql,infoxchange/puppetlabs-postgresql,puppetlabs/puppetlabs-postgresql,npwalker/puppetlabs-postgresql,DavidS/puppetlabs-postgresql,npwalker/puppetlabs-postgresql,infoxchange/puppetlabs-postgresql,buzzdeee/puppetlabs-postgresql,buzzdeee/puppetlabs-postgresql,infoxchange/puppetlabs-postgresql