[PWGEM] Add configurable for min. number of photons in EOI

[jokonig]

• This is to reduce the datasize of derived data. Use min. number of photons >= 2 for pi0 etc. analysis

[github-actions]

O2 linter results: ❌ 3 errors, ⚠️ 20 warnings, 🔕 0 disabled

[alibuild]

Auto-approving on behalf of @jokonig.

[alibuild]

Error while checking build/O2Physics/code-check for 2ee288d at 2026-09-01 17:28:

## sw/BUILD/O2Physics-code-check-latest/log
--
========== List of issues found ==========
++ echo 'Found 2 errors and 0 warnings.'
Found 2 errors and 0 warnings.
++ [[ 2 -gt 0 ]]
++ cat /sw/BUILD/81257a878131515f90b1bf4bb58184758d96ee7c/O2Physics-code-check/errors.txt
PWGEM/Dilepton/TableProducer/filterEoI.cxx:22:1: error: included header ASoAHelpers.h is not used directly [misc-include-cleaner,-warnings-as-errors]
PWGEM/Dilepton/TableProducer/filterEoI.cxx:32:1: error: included header Vector4D.h is not used directly [misc-include-cleaner,-warnings-as-errors]
++ [[ 0 -gt 0 ]]
++ [[ 2 -gt 0 ]]
++ exit 1
--

Full log here.