revert movement of unit alignment init to initializer list 

This fixes a bug unit aligment beeing ignored when creating a unit.

Setting this value in the initializer list has no effect becaue it is overwritten by advance_to().

this was changed in https://github.com/wesnoth/wesnoth/commit/30c179b92da29bb03541e8e0c7dfaf1c3c401b35#diff-af3fd7e884f8ab9f39f9088ca4010d0dR1738.