Support configuration of encryption used for LTPA keys generation

New LTPA keys after 25.0.0.2 are generated using AES-256 by default. However, those keys are not compatible with applications running on Liberty 25.0.0.1 or older. Provide a configuration option to allow users to generate/regenerate LTPA keys with AES-128 for such app instances. It could be configurable at the namespace level (in Operator ConfigMap).