[PWGHF] Implement workaround to for check in MlResponse not compatible with fixed features

[fgrosa]

This PR implements a workaround to the check introduced in #16424 which is not compatible in case of model application with a fixed array of features, not read by a configurable.

[github-actions]

O2 linter results: ❌ 0 errors, ⚠️ 8 warnings, 🔕 7 disabled

[alibuild]

Error while checking build/O2Physics/o2 for 03a6199 at 2026-06-17 15:55:

## sw/BUILD/O2Physics-latest/log
/sw/SOURCES/O2Physics/slc9_x86-64-slc9_x86-64/0/PWGHF/TableProducer/trackIndexSkimCreator.cxx:1730:29: error: 'struct std::array<o2::analysis::MlResponse<float>, 8>' has no member named 'cacheInputFeaturesIndices'
ninja: build stopped: subcommand failed.

Full log here.

[alibuild]

Auto-approving on behalf of @fgrosa.