Travis-CI: skip building mariadb-test packages to speed up build
Travis-CI: skip building mariadb-test packages to speed up build

The build must stay under the Travis-CI 50 minute limit. Currently
they often exceed, and the huge test suite is the single most long
step in moving/packaging files, so remove it on Travis-CI automatically.

natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2