core: remove addCanDoActionMessage calls to set variable replacements

Replace calls to addCanDoActionMessage which set variable replacements
in the message with calls to CommandBase#failCanDoAction method that
also gets variable replacements - it makes the code shorter and easier
to read.

Change-Id: Icd48fff9200efab6a2a30c7f03f4aa6b4404ad2f
Signed-off-by: Arik Hadas <ahadas@redhat.com>