headless services are not removed when cluster is deleted

[stang]

Since headless services were introduced in patroni/patroni#958, those need to be cleaned after a cluster is deleted.

Initial discussion with @CyberDem0n : patroni/patroni#1055 that led to this ticket.

Update:

As this fix won't cleanup already orphan services, I used this script to manually clean up the left overs.

[FxKu]

merged with 1f4267e