Use new encryption provider constants (reprise)

This is a follow-up of:
https://review.opendev.org/453144

and it fixes the last usage of the encryptor classes
which was introduced by https://review.opendev.org/472219
while the previous "clean-up" change was waiting to be merged.

Change-Id: I564d9f4d603c7f0dbfdde65dac1325c26fdff999
1 file changed