Make the DB URIs host-independent for all services

Make the DB URIs host-independent for all services

When fixing LP#1643487 we added ?bind_address to all DB URIs.
Since this clashes with Cellsv2 due to the URIs becoming host
dependent, we need a new approach to pass bind_address to pymysql
that leaves the DB URIs host-independent.

In change Iff8bd2d9ee85f7bb1445aa2e1b3cfbff1f397b18 we first create a
/etc/my.cnf.d/tripleo.cnf file with a [tripleo] section with the correct
bind-address option.

In this change we make sure that the DB URIs will point to the added
file and to the specific section containing the necessary bind-address
option. We do introduce a new MySQLClient profile which will hold all
this more client-specific configuration so that this change can fit
better in the composable roles work. Also, in the future it might
contain the necessary configuration for SSL for example.

Note that in case the /etc/my.cnf.d/tripleo.cnf file does not exist
(because it is created via the mysqlclient profile), things keep on
working as usual and the bind-address option simply won't be set, which
has no impact on hosts where there are no VIPs.

Co-Authored-By: Damien Ciabrini <dciabrin@redhat.com>
Change-Id: Ieac33efe38f32e949fd89545eb1cd8e0fe114a12
Related-Bug: #1643487
Closes-Bug: #1663181
Closes-Bug: #1664524
Depends-On: Iff8bd2d9ee85f7bb1445aa2e1b3cfbff1f397b18