As concluded from BF-46384 it's possible that the if there is a config index being built in progress, it still continues to be building even if the node loses the election and steps down. In such cases, it's possible that it can go through a step up and currently it would lead to attempt to create another config index that would be conflicting with the one that is in progress, which leads to a fatal failure. Ideally instead we should simply skip re-built of such index and wait for existing index build job to complete.