calamari_rest: work around restrictive grains permissions
calamari_rest: work around restrictive grains permissions

The cache of minion data doesn't actually require
root privileges, but the method that salt uses to
resolve a minion glob to minion IDs does.  Circumvent
this by using the private _get_cached_minion_data
function to get straight at what we want.

Fixes: #7783

r0h4n/ceph-integration