[FTS] UI: ns-server alerts interrupt and wipe out editing-in-progress index definitions

I got popup alerts from ns_server while building a custom index mapping on 4.6 on AWS. Each time, I lost my progress and had to start over - very annoying. Those particular messages were spurious and have been fixed MB-21533 but the issue needs to be fixed for FTS because presumably any alerts will trigger a loss of progress. We don't currently have save behavior and we probably don't want it, so I'm thinking there might be an intermediate solution that just avoids clearing the fields under the popup.

We need to do something about this so that innocent developers d