Only enable MySQL TRADITIONAL mode if we're running against MySQL
Only enable MySQL TRADITIONAL mode if we're running against MySQL

Change I2960435c81d21f5a65ea7fa4dc5c100880cf6aef, which enabled
MySQL TRADITIONAL mode, erroneously would attempt to enable that
MySQL-specific mode on both MySQL and DB2 connections. Only enable
TRADITIONAL mode when actually running against MySQL.

Change-Id: I28c40c47e2515112555f2abdd2ecc4dc5c3399f6

openstack/oslo.db,openstack/oslo.db,akash1808/oslo.db,vikt0rs/oslo.db,malor/oslo.db,varunarya10/oslo.db,magic0704/oslo.db,JioCloud/oslo.db