Clean things related to the index

[josecelano]

This repo has been forked from https://github.com/torrust/torrust-demo

That repo includes configuration to deploy the Torrust Tracker and Index as a whole solution.

I decided to split the two services (Tracker and Index) into two repos. This is the one for the tracker.

In this issue, I will only clean a few things related to the Index.