fix(ontap-nas-economy): enable prune tasks again

[clementnuss]

Change description

Enable housekeeping tasks again for trident-nas-economy driver.

Did you add unit tests? Why not?

The functions re-enabled by this patch were always unit-tested.

Does this code need functional testing?

Given the functionality of the individual housekeeping functions was unit-tested, this might not be needed.

Is a code review walkthrough needed? why or why not?

No, this is only a 2-lines change.

Does this code need a note in the changelog?

Enable housekeeping tasks again for trident-nas-economy driver.

Does this code require documentation changes?

Additional Information

cf #936