ATLASRECTS-7305: fixes for large cluster building

Closed Jean-Baptiste De Vivie De Regie requested to merge ATLAS-EGamma/athena:22_egCelss into 22.0

This MR fixes bugs in the large cluster builder tool in EGamma, used to keep rectangles of 7x11 (S2 granularity) cells in AOD (for central electron and photon studies) (Large clusters in the fwd region are also built for the purpose of keeping cells, but the bugs in that part should be harmless.)

This has no effect on reconstructed quantities, only the size of the AllCalo cell container in AOD should increase a bit, and maybe links from clusters to cells will be reshuffled.

Edited by Jean-Baptiste De Vivie De Regie

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