preparing switch to V11 HGCAL: GT and geometry

[franzoni]

The V11 HGCAL geometry will require:

--geometry Extended2026D46
--> D46 = T15+C9+M3+I10+O3+F2

and

auto:phase2_realistic_T15
--> see info in cms-sw/cmssw#27517

[franzoni]

documentation of geometries, useful to keep track of:
https://github.com/cms-sw/cmssw/blob/master/Configuration/Geometry/README.md

[clelange]

Thanks. The geometry info is also linked from the README.

@franzoni Do you intend to work on this? I think at this point we should keep both geometry options (i.e. not replace the options that we have here at the moment).

[rovere]

V11 is not yet fully validated and understood. I'd keep V10 for production with the option to switch to V11 once we are confident.

[franzoni]

I can look into making V10/V11 toggle-able

[clelange]

Thanks - it would just mean adding corresponding shell scripts such as the ones for D41 in https://github.com/CMS-HGCAL/reco-prodtools/tree/master/templates/python to that folder (see also what's written in those files).