Use "mid" stable id for condition cards conditionally.

When there is no suggestion, use "mid" stableId instead of "top"
stableId for the header card.

This avoid an animation jank: when user swipes away a suggestion, the
condition summary header moves up instead of disappears then reappears.

Old behavior:

---  Suggestion ---   --swipe-->     /// Top Header ///
///  Mid Header ///

New behavior:

--- Suggestion ---   -- swipe -->   /// Mid Header ///
/// Mid Header ///

(Notice the header id change)

Change-Id: I63512d3d21382488e43dddb8819fabe4af40d101
Fixes: 65729560
Test: robotests