[PWGLF] Add new workflow for event loss and store occupancy in the output

[GiorgioAlbertoLucia]

• Add a new workflow to compute the signal/event loss
• Handle properly the collision id in the processMC workflow
• Store occupancy information in the output table

[github-actions]

O2 linter results: ❌ 21 errors, ⚠️ 9 warnings, 🔕 0 disabled

[alibuild]

Error while checking build/O2Physics/code-check for 043c2e8 at 2026-08-21 18:57:

++ set -euo pipefail
++ [[ -d /sw/slc9_x86-64/Clang/v20.1.7-26 ]]
+++ realpath /sw/BUILD/ad27cb64a672defd720d26ce0c21c6102c4df11d/O2Physics-code-check/../../O2Physics-latest/O2Physics
++ O2PHYSICS_BUILDDIR=/sw/BUILD/e247a64d0303c433e49666bd45b1f9d6a9b9aebe/O2Physics
++ cp /sw/BUILD/e247a64d0303c433e49666bd45b1f9d6a9b9aebe/O2Physics/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")]))'
++ O2PHYSICS_SRC=/sw/SOURCES/O2Physics/slc9_x86-64-slc9_x86-64/0
++ pushd /sw/SOURCES/O2Physics/slc9_x86-64-slc9_x86-64/0
/sw/SPECS/slc9_x86-64/O2Physics-code-check/1.0-local115/O2Physics-code-check.sh: line 16: pushd: /sw/SOURCES/O2Physics/slc9_x86-64-slc9_x86-64/0: No such file or directory

Full log here.