CLI should not use the environment to find DUCC_HOME

DUCC_HOME should be defined by the location of the CLI jar the application uses, or by the location of the invoking script. If an environment variable takes precedence then a request could be sent to a ducc runtime from an incompatible CLI jar. For the same reason if the DUCC_HOME system property is set it must match the location of the invoking program.
Note that any environment variable including DUCC_HOME may be used by the CLI to resolve placeholders in the user's options.