Bug 1560339 - Extra incoherent logging when running android mochitest r=gbrown

Do not decode data returned by get_file() in adb.py

Differential Revision: https://phabricator.services.mozilla.com/D38844

--HG--
extra : moz-landing-system : lando

testing/mozbase/mozdevice/mozdevice/adb.py

@@ -2289,12 +2289,12 @@ class ADBDevice(ADBCommand):
                 # instead read only the requested portion of the local file
                 if offset is not None and length is not None:
                     tf2.seek(offset)
-                    return tf2.read(length).decode("UTF-8", "replace")
+                    return tf2.read(length)
                 elif offset is not None:
                     tf2.seek(offset)
-                    return tf2.read().decode("UTF-8", "replace")
+                    return tf2.read()
                 else:
-                    return tf2.read().decode("UTF-8", "replace")
+                    return tf2.read()
 
     def rm(self, path, recursive=False, force=False, timeout=None, root=False):
         """Delete files or directories on the device.