[PWGHF] add flag to store only soft-pi tracking info.

[mfaggin]

The new flag Configurable<bool> trackingInfo4SoftPiOnly allows us to fill the trackingi nfo only for the soft-pion track and we can rerun and study the tracking systematics only focusing on the soft pion.

@arossi81 @Mingyu3360715

[github-actions]

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

[alibuild]

Error while checking build/O2Physics/code-check for eb03e04 at 2026-09-04 13:45:

## sw/BUILD/O2Physics-code-check-latest/log
--
========== List of issues found ==========
++ echo 'Found 1 errors and 6 warnings.'
Found 1 errors and 6 warnings.
++ [[ 1 -gt 0 ]]
++ cat /sw/BUILD/9a4e0e496ad9c566364386d866bc5affb153afed/O2Physics-code-check/errors.txt
PWGHF/D2H/Tasks/taskSigmac.cxx:938:5: error: switching on non-enum value without default case may not cover all cases [bugprone-switch-missing-default-case,-warnings-as-errors]
++ [[ 6 -gt 0 ]]
++ cat /sw/BUILD/9a4e0e496ad9c566364386d866bc5affb153afed/O2Physics-code-check/warnings.txt
PWGHF/D2H/Tasks/taskSigmac.cxx:149:41: warning: implicit conversion 'bool' -> 'int' [readability-implicit-bool-conversion]
PWGHF/D2H/Tasks/taskSigmac.cxx:149:60: warning: implicit conversion 'bool' -> 'int' [readability-implicit-bool-conversion]
PWGHF/D2H/Tasks/taskSigmac.cxx:149:81: warning: implicit conversion 'bool' -> 'int' [readability-implicit-bool-conversion]
PWGHF/D2H/Tasks/taskSigmac.cxx:154:39: warning: implicit conversion 'bool' -> 'int' [readability-implicit-bool-conversion]
PWGHF/D2H/Tasks/taskSigmac.cxx:154:56: warning: implicit conversion 'bool' -> 'int' [readability-implicit-bool-conversion]
PWGHF/D2H/Tasks/taskSigmac.cxx:154:75: warning: implicit conversion 'bool' -> 'int' [readability-implicit-bool-conversion]
++ [[ 1 -gt 0 ]]
++ exit 1
--

Full log here.