[viz] Revert dropna logic for pivot tables (#8040)
[viz] Revert dropna logic for pivot tables (#8040)


zhouyao1994/incubator-superset,airbnb/caravel,apache/incubator-superset,airbnb/caravel,zhouyao1994/incubator-superset,apache/incubator-superset,apache/incubator-superset,airbnb/superset,mistercrunch/panoramix,airbnb/caravel,zhouyao1994/incubator-superset,airbnb/caravel,apache/incubator-superset,airbnb/superset,mistercrunch/panoramix,mistercrunch/panoramix,zhouyao1994/incubator-superset,mistercrunch/panoramix,apache/incubator-superset,zhouyao1994/incubator-superset,airbnb/superset,airbnb/superset