DataModel: improve DataHeader formatter

[ktf]

Add splitPayloadIndex / splitPayloadParts to the default printout

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• #14910 (2 commits)
• -> #14911 (2 commits)
• #14859 (2 commits)

[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 async-2024-PbPb-apass1 async-2024-ppRef-apass1 async-2024-PbPb-apass2 async-2023-PbPb-apass5

[alibuild]

Error while checking build/O2/fullCI_slc9 for c9e9cc830ff52941509c90cf37e8022533adb374 at 2025-12-11 17:46:

## sw/BUILD/O2-full-system-test-latest/log
command o2-sim --field=ccdb --seed 12345 -j 32 -n 100 -m PIPE ITS MFT FT0 FV0 FDD -g extgen -e TGeant4 --configKeyValues "GeneratorExternal.fileName=$O2_ROOT/share/Generators/external/QEDLoader.C;QEDGenParam.yMin=-7;QEDGenParam.yMax=7;QEDGenParam.ptMin=0.001;QEDGenParam.ptMax=1.;${SIMOPTKEY}" --run 310000 had nonzero exit code 139


## sw/BUILD/o2checkcode-latest/log
--
========== List of errors found ==========
++ GRERR=0
++ grep -v clang-diagnostic-error error-log.txt
++ grep ' error:'
++ GRERR=1
++ [[ 1 == 0 ]]
++ mkdir -p /sw/INSTALLROOT/55ced40990c08395a68ba6a083bc1eeb30bc6861/slc9_x86-64/o2checkcode/1.0-local41/etc/modulefiles
++ cat
--

Full log here.