Can't create an entity after all its fields decryption and module removal

I tried to remove some field_storage_definitions related to the field_encrypt module in the key_value table (during module uninstallation). After that, I was able to create new users.
I created a Merge request with my changes.

Here's the patch if someone needs it.

@rsych thanks for your patch, it works fine for me, however, it seems to me that we can provide some code changes.