add optional TARGET=.. parameter for 'make containerized-test'
add optional TARGET=.. parameter for 'make containerized-test'

Running the containerized-tests is relatively time consuming as it runs
all the tests. By adding a TARGET=.. option to the Makefile, it is now
possible to run a selected test, for example:

    make containerized-test TARGET=static-check

This reduces the time the tests take, so it is more friendly to the
developers while addressing problems.

When no TARGET=.. parameter is passed, the default tests are run.

Signed-off-by: Niels de Vos <7bda0c0ee7f47171cc808e9e60292cbc5d8140dd@redhat.com>

ceph/ceph-csi,ceph/ceph-csi,ceph/ceph-csi,ceph/ceph-csi