\small { (a) Trigger efficiency for neutral clusters, narrow clusters, and isolated narrow clusters for the L1-$\gamma$-low and -high calorimeter triggers. (b) Trigger rejection factor calculated with and without applying the trigger efficiency for each of the calorimeter triggers. The results of a constant fit to the rejection factor plateau regions are shown in the legend, while the estimation of the uncertainties are described in Sect. \ref{sec:sys_unc} }.