BLS Trigger: Code Cleanup

• Delete TrigL2TrkMassFex and TrigL2TrkMassHypo as they appear to be unreferenced and unused
• Clear up uses of TrigVertexCollection
• Rework mass calculation methods to avoid malloc.
• Remove old unused helper methods
• Remove excess comments
• Remove unused references to VKalVrt (save memory in private tool regime)
• Remove elements for cancelled FTK elements
• Remove unused variables identified by cppcheck
• Rework includes using advice from include-what-you-use
• Clang-tidy autofix performance - loop through reference to avoid copying non-trivial objects

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• compile time 1-thread 23m7.663s to 20m50.111s
• lib size 7.3M to 6.8M dbg 362M to 333M

cc @tursom @lyubushk for comment