[refactor][shortfin_apps]: remove unused img_metadata property (#1056)

Author: bjacobgordon

shortfin/python/shortfin_apps/flux/components/messages.py

@@ -101,7 +101,6 @@ def __init__(
         self.image_array = image_array
 
         self.result_image = None
-        self.img_metadata = None
 
         self.done = sf.VoidFuture()
 

shortfin/python/shortfin_apps/sd/components/messages.py

@@ -91,7 +91,6 @@ def __init__(
         self.image_array = image_array
 
         self.result_image: Union[str, None] = None
-        self.img_metadata = None
 
         self.done = sf.VoidFuture()