cephadm: create ceph-exporter sock dir if it's not present

cephadm: create ceph-exporter sock dir if it's not present

Since this is usually /var/run/ceph/ which ends up getting
created by other daemons as well, it was common to see
ceph-exporter fail to deploy and then deploy fine after
once other daemons were down on the host. I don't see any
reason we can't just try to make the directory here instead
of bailing out.

Fixes: https://tracker.ceph.com/issues/64491wq
Signed-off-by: Adam King <adking@redhat.com>