Label property is not being replaced in Real-Time and Big Data Analytics when items are reused

[chris-fox]

When you deploy a solution with a Real-Time or Big Data Analytic and the analytics have Feed or Feature Layer inputs that were already created from a previous deployment the label property in the analytic definition is not being replaced. As a result in the UI see something like below:

To reproduce:

1. Deploy this item https://localdeployment.maps.arcgis.com/home/item.html?id=a68ec9adb4da43458e37c4aa57f3186d.
   This creates the feeds and feature layers and other Velocity items. If you open the Sweeper Tracker Realtime Analytic and edit it all the labels for Feeds and Feature layers are updated properly.
2. Deploy this item https://localdeployment.maps.arcgis.com/home/item.html?id=f08dd452ce504f4aac33de3d5be79574 and enable the option to reuse existing items
   This will reuse the Feeds and Feature layers created in the previous deployment but create a new Real-Time Analytic. If you edit the Mower Vehicle analytic in Velocity you will see the labels of the Feeds and Feature Layers still contain the variable syntax: {{8191c13d656a4a97a83f30f09d13543f.label}}

The other properties of the analytic are being correctly replaced using the existing items.