master-qa-11785

https://issues.liferay.com/browse/LIFERAYQA-11785

Hi Brian, this pull is to allow us to write SAML tests that require 2 separate instances of liferay on 2 separate databases.

I wasn't able to cherry pick into ee-6.1.x from ee-6.2.x, and I wasn't able to cherry-pick from ee-6.1.x into ee-6.1.30, so you'll have to specifically fetch the ee-6.1.x and ee-6.1.30 pulls.

In my pull, I did the following (broken up by these commits)
1. I renamed the variables in "prepare-additional-bundles" to match the variables from "run-simple-server"
2. I split up "app.server.bundles.size" and "cluster.enabled" because they don't always go together. There will be times when we want multiple instances of liferay but not for clustering.
3. I added the logic for creating multiple databases. I followed the same format as what was already existing in "run-simple-server" and "prepare-additional-bundles". That's why I used "databases.size" and "database.index". Let me know if you prefer different names.
4. Since I wanted to reuse "set-app-server-properties", I renamed "app.server.bundle.index" to "index" to be more generic because I was also passing in "database.index". I talked this over with Hashi and "index" seemed to be ok since that attribute is only being used in that specific macrodef. Let me know if this should be changed back to app.server.bundle.index.