ci.cfg: Remove all the configurations for the 'release' branch

The 'release' branch is now dead as we will switch to the new branching scheme.

Change-Id: If95515f2f17f9337cdb03ca67484f7909ead72ff
Reviewed-by: Simo Fält <simo.falt@digia.com>
qtqa: Add configurations for 5.3 branches

Get the configuration prepared before switching to the new braching model.

Change-Id: I9c24c1c32bdee39c664cbbf350a1935b92c11c06
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: Simo Fält <simo.falt@digia.com>