When changing the cluster configuration to scale it up or down, there is no warning if there's a index build currently running on the primary/secondary. I created an index, saw it finish on the primary and then scaled the cluster, without thinking about that the index is only now built on the secondary, too.

During the downscaling the index build got aborted and attempted to build in foreground then. However this for some reason did not work and I had to contact support to help me with getting the secondary up again.

My proposal would be to either:
- Display a warning when trying to change the cluster configuration that requires a reboot of the nodes, while an index build is currently in progress on one of the nodes
- Show the index build also for the secondaries in the "realtime" metrics to raise awareness that an index build is happening on the secondaries only after the primary has finished and to show progress for the secondaries as well.