Hanging pm data resources in etcd after reconcile

Following test steps were made:

• create and enable device(s) (one OLT with one PON and one ONU)
• do first sanity check
• restart open onu go adapter
• do second sanity check (without add subscriber)
• disable ONU device
• check ONU ports are disabled
• enable ONU device
• do third sanity check (without add subscriber)
• do teardown incl disable and delete device(s), check etcd data with prefix service/voltha_voltha/openonu are empty -> this failed, as well as Suite teardown

There are (in this case) thre hanging pm-data resources in etcd:
[ [

{'instances_active': [8708, 8709, 8710, 8707], 'instances_to_add': [], 'instances_to_delete': None}

,

{'instances_active': [257, 258, 259, 260], 'instances_to_add': [], 'instances_to_delete': None}

,

{'instances_active': [32769], 'instances_to_add': [], 'instances_to_delete': None}

] ]