make_rd_photons builder selection

In the photon selection done in make_rd_photons: https://gitlab.cern.ch/lhcb/Moore/-/blob/master/Hlt/Hlt2Conf/python/Hlt2Conf/lines/rd/builders/rdbuilder_thor.py the requirement ShowerShape_max = 1500 is too tight. This quantity represents the square of the width of the shower/cluster in the transverse plane (in mm^2). The distribution of this ShowerShape is quite different among the three Calorimeter regions due to very different cell sizes (40, 60, 120 mm for inner, middle and outer), but probably also due to different incident angle of the photons to the Calo plane. A cut on 1500 rejects almost all photons from the outer region and a large fraction from the middle region.
Therefore, this default value of 1500 should be increased. Although with a larger value, we'll only be removing background for clusters from the outer region. A cut on this quantity is useful if one can apply a different value per Calo region. Probably it would be better to remove this requirement from make_rd_photons and replace it by another requirement, for instance on E19, if available (which represents the energy ratio between the seed cell and the 3x3 cluster energy).
ShowerShape_MCRun3.pdf