core: Modify constructor to be compatible with caller

ProcessOvfUpdateForStorageDomainCommand is being called without context,
although the constructor is only supported with context parameter, so we
will always get runtime exception when being called.

The proposed fix remove the context from the
ProcessOvfUpdateForStorageDomainCommand constructor

Change-Id: Id4c1c7f36876b51d2194e69b95a3d7c20f43b659
Signed-off-by: Maor Lipchuk <mlipchuk@redhat.com>