Fix interface encryption password helper call time
Fix interface encryption password helper call time

The _get_key_file_encryption_password helper needs to be called
after the passed or keyid-based filepath has been determined, i.e.
after key creation in the latter case, because it might be
displayed on the password prompt.

Plus remove obsolete quotes.

secure-systems-lab/securesystemslib,secure-systems-lab/securesystemslib