Remove Tomcat Welcome Default App from Fineract Container

The Fineract Container currently includes the the Tomcat Welcome Default App (the usual same old, with that welcome page, it can currently be seen e.g. on https://demo.fineract.dev).

This is so so because it's in that Bitnami Base Image we currently use. It's a bit confusing when using the container, is totally unnecessary, eats a bit of memory, and bloats the container size (slightly).

It should be a trivial to yank it with an appropriate RUN rm ... in the Dockerfile.

FINERACT-730 will eventually change the deployment model and container, but until we (finally...) do that, and because that's a bit more work whereas this is be a quick low hanging fruit, we should still do this if anyone is wiling to pick this up.