Post-#3211 configuration file cleanup

Following the merge of #3211, remove
* Obsolete CkfTrajectoryBuilder ESProducer configuration files
* Obsolete TrajectoryFilter ESProducer configuration files
* Bunch of other obsolete configuration files
```
RecoParticleFlow/PFTracking/python/convBrem_cff.py
RecoPixelVertexing/PixelLowPtUtilities/python/MinBiasTracking_cff.py
RecoPixelVertexing/PixelLowPtUtilities/python/common_cff.py
RecoPixelVertexing/PixelLowPtUtilities/python/firstStep_cff.py
RecoPixelVertexing/PixelLowPtUtilities/python/secondStep_cff.py
RecoPixelVertexing/PixelLowPtUtilities/python/thirdStep_cff.py
RecoTracker/ConversionSeedGenerators/python/PhotonConversionTrajectorySeedProducerFromQuadruplets_cff.py
RecoTracker/ConversionSeedGenerators/python/PhotonConversionTrajectorySeedProducerFromSingleLeg_cff.py
RecoTracker/ConversionSeedGenerators/python/PhotonConversionTrajectorySeedProducerFromSingleLeg_gsf_cff.py
RecoTracker/IterativeTracking/python/LargeD0_PixelPairStep_cff.py
RecoTracker/IterativeTracking/python/LargeD0_PixelTibTidTecStep_cff.py
RecoTracker/IterativeTracking/python/LargeD0_PixelTripletStep_cff.py
RecoTracker/IterativeTracking/python/LargeD0_TibTidTecStep_cff.py
RecoTracker/IterativeTracking/python/LargeD0_TobTecStep_cff.py
```
All of the above (except ```MinBiasTracking_cff.py```, ```common_cff.py```, and ```firstStep_cff.py```) produce errors if run with ```python file.py``` indicating they're not used in any standard workflows (@cerati gave +1 for removing them). Removal of ```secondStep_cff.py``` and ```thirdStep_cff.py``` would make ```MinBiasTracking_cff.py``` erroneous, and ```common_cff.py``` and ```firstStep_cff.py``` are imported only in ```MinBiasTracking_cff.py``` so I removed them as well.