Remove unused b-tagging configuration

This removes a substantial fraction of the configuration code for b-tagging. It shouldn't change anything, since all this code is dead.

I wasn't able to remove BTaggingFlags or BTaggingConfiguration completely: these are apparently used to set the AOD output collections somewhere. But I was able to remove 90% of the code in them. I also had to remove some code in the jet configuration that was manipulating BTaggingFlags but not actually doing anything.

I ran a diff over a few hundred events with and without this change, it made no difference (as expected).

Attention @duperrin