Add ability to remove storage configuration from a tenant

At the moment, each type of storage provides a `SetXXXConfiguration` method to set storage configuration for a definition against a tenant. We need a corresponding method to remove this configuration to support tenant unenrollment.

Start by locating the existing SetXXXConfiguration methods for each storage type and trace how tenant-specific configuration is stored. Add the corresponding removal behavior for every storage type, then verify that a tenant can be unenrolled without its storage configuration remaining.

Written by the indexing model from the issue text.