This is the name of a Pannonian tribe who flourished in the Greco-Roman days in the region of the River Drava.
It strikes me that, as ‘z’ is often the equivalent to ‘d’ in the names of this region, an *adali could maybe related to the Germanic word found in German ‘edel’ and Old English ‘æþele’, both meaning ‘noble’. The Germanic word has a possible Indo-European origin, but I believe no recognised cognates in any other IE language. Could Pannonian provide such a cognate?
As a point of comparison, the terrifying northern Germanic tribe of the Heruli or Eruli had a name related to Old English ‘eorl’ (noble) and were thus ‘the noble ones’.