Single commits are not re-created if keys are encrypted

[shuse2]

Expected behavior

When enabling block generation, single commits should be re-generated from non certified heights

Actual behavior

Only if keys are not encrypted, while node is restarting it creates the single certificates

Steps to reproduce

Check if the single certificates are created when starting the node with generators with keys encrypted

Which version(s) does this affect? (Environment, OS, etc...)

6.0.0-rc.1