Remove Krona-LCA from workflow and required databases

[florianzwagemaker]

The Krona-LCA gives errors like https://github.com/marbl/Krona/issues/137 and https://github.com/marbl/Krona/issues/139. We also see it in our logs. Since we already have an LCA method via MgKit, which produces an LCA with "better" results... we don't actually need the Krona-specific LCA.

All we need is the script that creates the Krona-chart, which is compatible with the LCA generated by MgKit. I'd suggest it's best to simply remove it.