Fix pixelTracks imports

[makortel]

This PR is a follow-up to #17438 adding a pixelTracks_cfi that imports from descriptions-generated pixelTracksDefault_cfi, and changing all affected files to import from `pixelTracks_cfi. This should have been done already in #17170, but somehow I missed it.

The PixelTracksL2Tau_cfi (*) referenced TrackingRegionsFromBeamSpotAndL2Tau (in pre-#17170 way), so I added TrackingRegionsFromBeamSpotAndL2TauEDProducer to produce the TrackingRegions to event as required by the new seeding framework. I'm not sure how useful PixelTracksL2Tau_cfi is anymore though, as now it has just a clone of PixelTracksProducer and a TrackingRegionsFromBeamSpotAndL2TauEDProducer module via import (i.e. hit doublet/triplet/quadruplet producers and filter+fitter+cleaner are missing).

(*) I guess this is being used for ConfDB parsing since it was modified in #17438.

Tested in 9_0_0_pre3, no changes expected.

@rovere @VinInn @Martin-Grunewald

[makortel]

@cmsbuild, please test

[cmsbuild]

The tests are being triggered in jenkins.
https://cmssdt.cern.ch/jenkins/job/ib-any-integration/17714/console Started: 2017/02/09 13:24

[cmsbuild]

A new Pull Request was created by @makortel (Matti Kortelainen) for CMSSW_9_0_X.

It involves the following packages:

RecoPixelVertexing/PixelTrackFitting
RecoTauTag/HLTProducers
RecoTracker/TkSeedGenerator

@perrotta, @cmsbuild, @silviodonato, @cvuosalo, @fwyzard, @Martin-Grunewald, @slava77, @davidlange6 can you please review it and eventually sign? Thanks.
@ghellwig, @felicepantaleo, @GiacomoSguazzoni, @rovere, @VinInn, @mschrode, @gpetruc, @dgulhan this is something you requested to watch as well.
@davidlange6, @smuzaffar you are the release manager for this.

cms-bot commands are listed here #13028

[cmsbuild]

+1
Tested at: 47a7493
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-17470/17714/summary.html

[cmsbuild]

Comparison job queued.

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-17470/17714/summary.html

[silviodonato]

+1

[slava77]

+1

for #17470 47a7493

• mainly a technical update
• jenkins tests pass and comparisons with baseline show no differences

[slava77]

+1
missed originally in the #17470 (comment)

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_9_0_X IBs (tests are also fine). This pull request requires discussion in the ORP meeting before it's merged. @davidlange6, @smuzaffar

[davidlange6]

+1