Move b-tagging options into b-tagging config flags

The configuration for b-jet trigger had a few overrides which were hardcoded in the runHLT_standalone.py job options fragment. Since we're moving away from job options fragments in general, I moved these to BTaggingConfigFlags. This might be of interest to @lbeemste who is currently working on the "new" configuration code: with this change the b-jet setup is correct in the new configuration by default and he should have one less thing to worry about.

While I was there I noticed an option called PrimaryVertexCollectionName which was only used in one configuration file, and on further inspection I think that configuration file isn't used anywhere else. So I deleted both the option and the file that uses it. This might be interesting to @bdong and @duperrin but it should change absolutely nothing in terms of b-tagging outputs.

No new features added, no outputs should change. This is just cleanup.