ci: fold 32 and 64 bit jobs together

ci: fold 32 and 64 bit jobs together

We currently construct a single container for each distro, which is
capable of running both 32 and 64 bit builds.

In addition, since we're meson only (which allows only out-of-tree
builds) we can do multiple builds for a given checkout.

As result we hammer the docker registry and distribution/package servers
a bit less.

Notes:
 - 32bit distcheck is disabled - not particularly interesting
 - 32bit tests are disabled for everyone - they are consistently failing

Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Link: https://github.com/kmod-project/kmod/pull/362
Signed-off-by: Lucas De Marchi <lucas.de.marchi@gmail.com>