Speed modifications to PrLongLivedTracking

Change in y tolerance of PrLLT for the initial hit search. Leads to a significant speedup (expected 40%) with mostly constant efficiency (slightly better for low momentum, maybe a tiny bit worse for high momentum, but all sub-percent and subject to tuning in the future).

Also implements a smarter selection of the initial sectors to look at.

NB: This algorithm is going to be replaced in the medium term. These are just quick changes to improve the throughput.

Before:

DownMCCheck          INFO Results
DownMCCheck          INFO **** Downstream                     1029225 tracks including         321373 ghosts [31.22 %], Event average 27.17 % ****
DownMCCheck          INFO   01_UT+T                         :  628562 from   855987 [ 73.43 %]     22 clones [ 0.00 %], purity: 99.43 %, hitEff: 99.00 %
DownMCCheck          INFO   02_UT+T>5GeV                    :  464431 from   552264 [ 84.10 %]     16 clones [ 0.00 %], purity: 99.44 %, hitEff: 99.15 %
DownMCCheck          INFO   03_UT+T_strange                 :   51006 from    78668 [ 64.84 %]      4 clones [ 0.01 %], purity: 99.40 %, hitEff: 98.68 %
DownMCCheck          INFO   04_UT+T_strange>5GeV            :   30988 from    40183 [ 77.12 %]      3 clones [ 0.01 %], purity: 99.41 %, hitEff: 98.88 %
DownMCCheck          INFO   05_noVelo+UT+T_strange          :   24604 from    40862 [ 60.21 %]      1 clones [ 0.00 %], purity: 99.38 %, hitEff: 98.62 %
DownMCCheck          INFO   06_noVelo+UT+T_strange>5GeV     :   16077 from    22219 [ 72.36 %]      1 clones [ 0.01 %], purity: 99.41 %, hitEff: 98.88 %
DownMCCheck          INFO   07_UT+T_fromB                   :   43530 from    55952 [ 77.80 %]      0 clones [ 0.00 %], purity: 99.50 %, hitEff: 99.21 %
DownMCCheck          INFO   08_UT+T_fromB>5GeV              :   36640 from    42946 [ 85.32 %]      0 clones [ 0.00 %], purity: 99.52 %, hitEff: 99.35 %
DownMCCheck          INFO   09_noVelo+UT+T_fromB            :    1643 from     2818 [ 58.30 %]      0 clones [ 0.00 %], purity: 99.42 %, hitEff: 98.68 %
DownMCCheck          INFO   10_noVelo+UT+T_fromB>5GeV       :    1025 from     1422 [ 72.08 %]      0 clones [ 0.00 %], purity: 99.48 %, hitEff: 98.96 %
DownMCCheck          INFO   11_UT+T_SfromDB                 :    1364 from     2003 [ 68.10 %]      0 clones [ 0.00 %], purity: 99.53 %, hitEff: 99.11 %
DownMCCheck          INFO   12_UT+T_SfromDB>5GeV            :     877 from     1139 [ 77.00 %]      0 clones [ 0.00 %], purity: 99.54 %, hitEff: 99.12 %
DownMCCheck          INFO   13_noVelo+UT+T_SfromDB          :     735 from     1171 [ 62.77 %]      0 clones [ 0.00 %], purity: 99.55 %, hitEff: 99.23 %
DownMCCheck          INFO   14_noVelo+UT+T_SfromDB>5GeV     :     510 from      708 [ 72.03 %]      0 clones [ 0.00 %], purity: 99.59 %, hitEff: 99.36 %
DownMCCheck          INFO   15_noVelo+UT+T_electrons        :   41964 from    88245 [ 47.55 %]      0 clones [ 0.00 %], purity: 99.26 %, hitEff: 97.65 %
DownMCCheck          INFO   16_noVelo+UT+T_electrons_P>5GeV :   23957 from    39525 [ 60.61 %]      0 clones [ 0.00 %], purity: 99.31 %, hitEff: 97.93 %

with this MR:

DownMCCheck          INFO Results
DownMCCheck          INFO **** Downstream                     1039949 tracks including         317746 ghosts [30.55 %], Event average 26.56 % ****
DownMCCheck          INFO   01_UT+T                         :  639145 from   855987 [ 74.67 %]     21 clones [ 0.00 %], purity: 99.45 %, hitEff: 99.10 %
DownMCCheck          INFO   02_UT+T>5GeV                    :  467098 from   552264 [ 84.58 %]     16 clones [ 0.00 %], purity: 99.45 %, hitEff: 99.20 %
DownMCCheck          INFO   03_UT+T_strange                 :   52709 from    78668 [ 67.00 %]      4 clones [ 0.01 %], purity: 99.42 %, hitEff: 98.85 %
DownMCCheck          INFO   04_UT+T_strange>5GeV            :   31420 from    40183 [ 78.19 %]      3 clones [ 0.01 %], purity: 99.42 %, hitEff: 98.95 %
DownMCCheck          INFO   05_noVelo+UT+T_strange          :   25293 from    40862 [ 61.90 %]      1 clones [ 0.00 %], purity: 99.40 %, hitEff: 98.74 %
DownMCCheck          INFO   06_noVelo+UT+T_strange>5GeV     :   16303 from    22219 [ 73.37 %]      1 clones [ 0.01 %], purity: 99.42 %, hitEff: 98.92 %
DownMCCheck          INFO   07_UT+T_fromB                   :   43889 from    55952 [ 78.44 %]      0 clones [ 0.00 %], purity: 99.51 %, hitEff: 99.24 %
DownMCCheck          INFO   08_UT+T_fromB>5GeV              :   36734 from    42946 [ 85.54 %]      0 clones [ 0.00 %], purity: 99.52 %, hitEff: 99.35 %
DownMCCheck          INFO   09_noVelo+UT+T_fromB            :    1661 from     2818 [ 58.94 %]      0 clones [ 0.00 %], purity: 99.41 %, hitEff: 98.62 %
DownMCCheck          INFO   10_noVelo+UT+T_fromB>5GeV       :    1026 from     1422 [ 72.15 %]      0 clones [ 0.00 %], purity: 99.49 %, hitEff: 98.88 %
DownMCCheck          INFO   11_UT+T_SfromDB                 :    1396 from     2003 [ 69.70 %]      0 clones [ 0.00 %], purity: 99.52 %, hitEff: 99.12 %
DownMCCheck          INFO   12_UT+T_SfromDB>5GeV            :     879 from     1139 [ 77.17 %]      0 clones [ 0.00 %], purity: 99.56 %, hitEff: 99.18 %
DownMCCheck          INFO   13_noVelo+UT+T_SfromDB          :     749 from     1171 [ 63.96 %]      0 clones [ 0.00 %], purity: 99.51 %, hitEff: 99.07 %
DownMCCheck          INFO   14_noVelo+UT+T_SfromDB>5GeV     :     510 from      708 [ 72.03 %]      0 clones [ 0.00 %], purity: 99.61 %, hitEff: 99.32 %
DownMCCheck          INFO   15_noVelo+UT+T_electrons        :   44169 from    88245 [ 50.05 %]      0 clones [ 0.00 %], purity: 99.31 %, hitEff: 98.03 %
DownMCCheck          INFO   16_noVelo+UT+T_electrons_P>5GeV :   24483 from    39525 [ 61.94 %]      0 clones [ 0.00 %], purity: 99.33 %, hitEff: 98.10 %

Refs. updated in Moore!555 (merged) Brunel!1039 (merged)