core: Remove Encr?ptionManagerMessages

There are two classes with this name, one with "y" and one with "i".
None of them is used.

Change-Id: I22a6c6a76e4be670d222fd701fcc63016653f813
Signed-off-by: Juan Hernandez <juan.hernandez@redhat.com>
(cherry picked from commit 5f112ba0549304a8e50e02f1b59aafb257170f56)