cleanup logic enhancement

[Payback159]

all namespaces which are created by tenama do have a label created-bywith the value tenama. At the moment the cleanup logic only checks if the namespace has the configured prefix in the name.

In this story the cleanup logic should be extended to check,

• if the namespace has the label created-by
• if the label created-byhas the value tenama

If both conditions are met, the namespace should be checked for it's duration.