Change pT5 rz chi2 cut definition into helix approximation (rebase PR40)

[ariostas]

This is a rebase of PR #40. Since it changes the performance I made it as its own PR so that we can compare the plots with the original PR.

[ariostas]

/run all

[github-actions]

The PR was built and ran successfully in standalone mode. Here are some of the comparison plots.

The full set of validation and comparison plots can be found here.

Here is a timing comparison:

   Evt    Hits       MD       LS      T3       T5       pLS       pT5      pT3      TC       Reset    Event     Short             Rate
   avg     40.9    384.6    191.2    127.0    135.1    501.4    117.8    243.5    102.0      3.2    1846.5    1304.2+/- 362.3     491.8   explicit[s=4] (target branch)
   avg     40.5    383.9    191.0    128.8    136.8    499.8    106.6    244.6    101.9      2.8    1836.7    1296.4+/- 358.2     488.5   explicit[s=4] (this PR)

[github-actions]

The PR was built and ran successfully with CMSSW. Here are some plots.

OOTB All Tracks

The full set of validation and comparison plots can be found here.