[PWGCF] flow-task: add mult vs centrality QA before sel8 (#9529)

Author: Luzhiyongg

PWGCF/Flow/Tasks/flowTask.cxx

@@ -217,6 +217,7 @@ struct FlowTask {
     registry.add("hMult", "Multiplicity distribution", {HistType::kTH1D, {{3000, 0.5, 3000.5}}});
     registry.add("hCent", "Centrality distribution", {HistType::kTH1D, {{90, 0, 90}}});
     if (!cfgUseSmallMemory) {
+      registry.add("BeforeSel8_globalTracks_centT0C", "before sel8;Centrality T0C;mulplicity global tracks", {HistType::kTH2D, {axisCentForQA, axisNch}});
       registry.add("BeforeCut_globalTracks_centT0C", "before cut;Centrality T0C;mulplicity global tracks", {HistType::kTH2D, {axisCentForQA, axisNch}});
       registry.add("BeforeCut_PVTracks_centT0C", "before cut;Centrality T0C;mulplicity PV tracks", {HistType::kTH2D, {axisCentForQA, axisNchPV}});
       registry.add("BeforeCut_globalTracks_PVTracks", "before cut;mulplicity PV tracks;mulplicity global tracks", {HistType::kTH2D, {axisNchPV, axisNch}});
@@ -675,6 +676,9 @@ struct FlowTask {
   void process(AodCollisions::iterator const& collision, aod::BCsWithTimestamps const&, AodTracks const& tracks)
   {
     registry.fill(HIST("hEventCount"), 0.5);
+    if (!cfgUseSmallMemory && tracks.size() >= 1) {
+      registry.fill(HIST("BeforeSel8_globalTracks_centT0C"), collision.centFT0C(), tracks.size());
+    }
     if (!collision.sel8())
       return;
     if (tracks.size() < 1)