Move db::mysql into service_config_settings

Move db::mysql into service_config_settings

This patch movs the various db::mysql hiera settings into a
'mysql' specific service_config_settings section for each
service so that these will only get applied on the MySQL service
node. This follows a similar puppet-tripleo change where we
create the actual databases for all services locally on
the MySQL service node to avoid permission issues.

Change-Id: Ic0692b1f7aa8409699630ef3924c4be98ca6ffb2
Closes-bug: #1620595
Depends-On: I05cc0afa9373429a3197c194c3e8f784ae96de5f
Depends-On: I5e1ef2dc6de6f67d7c509e299855baec371f614d