Change the execution order in update workflow

Currently the update workflow performs first install and then uninstall.
This can be problematic when reinstalling node-instance, and while trying to install it again we may get an error because some of the resources are still taken by the existing node-instance that should be uninstalled.
The default behavior should be first uninstalling all node-instances and only then installing.
A new flag called "uninstall_first" will allow to execute in the original order.