I faced the same problem while I did Hoth bonus series. I couldn't find a group for this quest so I decided to solo it and I also got into that "droids healing each other" trap) So I decided just to kill those packs of droids which included only 1 or 2 healing droids. Its seemes that the healing droids heal the big ones or each other only when they stand near) So I went to the left side of the road (considering i went from the base where i got the quest) to kill the first pack of the droid which included 2 big droids and 1 healing one. I killed big droids first and only after that killed the healing one (there is a tricky part here, the healing droid in this pack stands near one of the big droids, so I would suggest to push/pull the big droid away from the healing one and kill it there, or stun the healing droid). After that I picked up the datacore and 2 droid plans from the datapads nearby. Then I went to the right side of the road, again killed the big droids (the healing droid was far away in this pack), then the healing one and again pick up a datacore and 2 droid plans from datapads nearby. Then I went further into the area from the right side of the road and kill 1 patroling healing droid, got 1 irrepearable droid part (or whatever it's called). After that there stood a pack with one big and two healing droids but they all were far away from each other. So I killed the big one first and after two healing droids, collected irrepearable droid parts. Then I got back to the road, by that time two packs of droids I killed were respawned. So I repeated it all untill I got all the datacores, plans and parts. I soloed it with my fresh 50 guardian tank in tionese gear and a healing companion.