chore: improve clean up pipeline

[vilit1]

Ensure clean up pipeline also purges keyvaults. Purge allows us to reuse keyvault names (and avoid clashing between pipeline runs).

To allow purging, the no-wait for keyvault deletion has been removed.

The general clean-up is kept as a backup for missed resources from az iot ops delete (ex: the command fails).
 
 Keyvaults after the cleanup pipeline:

 Note: the extra keyvault prefix input is temporary and will be removed once we have all keyvaults using the same one again (we had to diverge and use different ones due to clashes)

Note 2: Since the purge has a --no-wait, the purge may take some time and the results are not instantaneous.

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