Final tweaks for the MCP winter recommendations

Hi everybody,

I open this MR to get the final tweaks needed for the winter update of the MCP winter recommendations into 21.2 following up !20096 (merged). The changes include

• Update to the latest calibration area of MuonEfficiencyCorrections
• Exchange the property useLowPtThreshold - which is an expert property and no user should touch it - by useLowPtMap
• That change is needed because the isolation scale-factors also now include a low-pt map for muons between 3-4 GeV which is totally different from the used threshold of 15 GeV for Zmumu reconstruction. To prevent the user of making any real dull mistake the property is now boolean and the thresholds can no longer be changed.

Adding @szambito, @fsforza, @nkoehler and the guard of athena @atlasbot

PhysicsAnalysis/MuonID/MuonIDAnalysis/MuonEfficiencyCorrections/MuonEfficiencyCorrections/MuonEfficiencyScaleFactors.h

@@ -168,7 +168,7 @@ namespace CP {
             std::string m_calibration_version;
 
             /// threshold below which low-pt SF (i.e. from JPsi) should be used
-            float m_lowpt_threshold;
+            bool m_use_low_pt_map;
          
             CP::SystematicSet m_affectingSys;