ITS: speedup final step in vertexer

[f3sch]

@shahor02 this sets the preliminary Pb-Pb as default in the Config and overwrites for pp with the (rounded) settings I sent you.

[alibuild]

Error while checking build/O2/fullCI_slc9 for 7cfe145 at 2026-04-16 07:56:

++ cp /sw/slc9_x86-64/O2/slc9_x86-64-slc9_x86-64-local11/compile_commands.json .
+++ python3 -c 'import json, os; print(os.path.commonpath([x["file"] for x in json.loads(open("compile_commands.json").read()) if "sw/BUILD" not in x["file"] and "G__" not in x["file"] and x["file"].endswith(".cxx")]))'
++ O2_SRC=/sw/SOURCES/O2/slc9_x86-64-slc9_x86-64/0
++ [[ -e /sw/SOURCES/O2/slc9_x86-64-slc9_x86-64/0/CMakeLists.txt ]]

Full log here.

[f3sch]

@shahor02 any idea why the matching crashed in the CI? I don't see how it is related to this code for the moment.

[shahor02]

@shahor02 any idea why the matching crashed in the CI? I don't see how it is related to this code for the moment.

@f3sch where do you see this? I see that the gcc was killed in O2Physics building, apparently due to the memory problems.

[f3sch]

@shahor02 any idea why the matching crashed in the CI? I don't see how it is related to this code for the moment.

@f3sch where do you see this? I see that the gcc was killed in O2Physics building, apparently due to the memory problems.

In the aarch64 (which I know is not required)

[shahor02]

Hm, no idea, but it was failing there already yesterday. I'll run locally full_CI