[EMCAL-670] EMCAL Clusterizer: change behavior for no gradient cut

[mhemmer-cern]

• Changed getClusterFromNeighbours so that when gradient gut is off, it now still adds neighbouring cells. Before this change when gradient cut was set to false all clusters were single cell cluster made only from the seed cell.
• Disabling the gradient cut means now that there can be any number of local maxima, so just like with the V1 clusterizer.

[github-actions[bot]]

REQUEST FOR PRODUCTION RELEASES: To request your PR to be included in production software, please add the corresponding labels called "async-" to your PR. Add the labels directly (if you have the permissions) or add a comment of the form (note that labels are separated by a ",")

+async-label <label1>, <label2>, !<label3> ...

This will add <label1> and <label2> and removes <label3>.

The following labels are available async-2023-pbpb-apass4 async-2023-pp-apass4 async-2024-pp-apass1 async-2022-pp-apass7 async-2024-pp-cpass0

[mhemmer-cern]

I made a check comparing the kV3Default clusterizer output before and after this change and they are similar, while NoSplit clusterizer now can add more cells to the cluster, so everything seems to be working as we wanted. https://its.cern.ch/jira/browse/EMCAL-1149

[mhemmer-cern]

hello @ktf Could you check this PR please, there are minor changes to the EMCal code, but build/O2/o2_slc9 fails and I am pretty sure it is not because of my changes. If that is the case could you merge it, please?