MDEV-31118: Rework Salsa-CI YAML work again

Salsa-CI file has got in malfunction state and
if fails with YAML error:
 mariadb-10.3 with Buster backports upgrade job:
 undefined need: build buster-backports

Also remove Salsa-CI MariaDB 10.3 double
upgrade target.

There is also several upgrades which makes
test green again.

NOTE TO MERGER: This is only up-to MariaDB 10.10.

Remove