Use `initialNumToRender` property + simplify our messaging FlatList.
Use `initialNumToRender` property + simplify our messaging FlatList.

see https://facebook.github.io/react-native/docs/flatlist#initialnumtorender

Signed-off-by: Andrey Shovkoplyas <b713972e59b8e606e23253c4a13e948139fea4d1@gmail.com>

status-im/status-react,status-im/status-react,status-im/status-react,status-im/status-react,status-im/status-react,status-im/status-react,status-im/status-react,status-im/status-react