[fsii]

1. Update MC particle - track match (remove use of double-sliceBy)
2. Delete rest C_CS and C_SV, both were added by PR15976 to avoid errors on macOS-arm (pass on Linux-x64), modified back to HIST by PR18584

[github-actions]

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

[Copilot]

🟢 Approval recommended

No active review issues are reported for the particle–track matching update.

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What changed in this PR

Updates Monte Carlo particle–track matching in the event-by-event particle-number fluctuation task, replacing nested slicing with explicit collision filtering.

Changes:

• Slice ungrouped tracks by MC particle, then filter by collision for mini-table storage and analysis.
• Count collision-matched tracks explicitly for acceptance checks and quality-assurance histograms.
• Replace the remaining C_CS and C_SV wrappers with direct HIST calls and make minor C++ cleanups.

File	Description
PWGCF/​EbyEFluctuations/​Tasks/​partNumFluc.cxx	Revises MC particle–track matching and removes histogram macro wrappers.

_{Review effort: Balanced}