YADE should not set values from Credential Store implicitly

Current Situation

• YADE supports cs://(CredentialStore) syntax
• If an option is not set explicitly, then YADE tries to set the option value implicitly, e.g. sets host, port, user values by extracting/analizing the Credential Store Url field etc.

Desired Behaviour

• YADE should set values from a Credential Store only if explicitly specified by the configuration.

Maintainer Notes

• The desired behavior is incompatible to some extent: with previous YADE version missing configuration items as e.g. the "source_user" or "source_host" have automatically been populated from a Credential Store.
• With this fix all configuration items have to be specified explicitly. However, we consider the previous behavior an error as implicit configuration causes unwanted side effects.