TrackReference: possibility to have unknown DetectorID

[sawenzel]

We've been using 0 as detectorID in generic "Stopping" TrackReferences. Unfortunately, 0 is also the ID of the ITS sensitive detector according to o2::detectors::DetID class.
The commit changes this to using -1, where -1 means simply means "unknown".

[github-actions]

REQUEST FOR PRODUCTION RELEASES:
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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 adb9828 at 2025-07-09 20:17:

## sw/BUILD/4ca51307b106213ce7ad18dea3427170d8d6aafc-latest/log
/sw/slc9_x86-64/YODA/yoda-2.1.0-6/include/YODA/highfive/H5Object.hpp:13:10: fatal error: H5Ipublic.h: No such file or directory
make[3]: *** [Makefile:563: libRivetCore_la-Run.lo] Error 1
make[3]: *** Waiting for unfinished jobs....
/sw/slc9_x86-64/YODA/yoda-2.1.0-6/include/YODA/highfive/H5Object.hpp:13:10: fatal error: H5Ipublic.h: No such file or directory
make[3]: *** [Makefile:633: libRivetCore_la-AnalysisHandler.lo] Error 1
/sw/slc9_x86-64/YODA/yoda-2.1.0-6/include/YODA/highfive/H5Object.hpp:13:10: fatal error: H5Ipublic.h: No such file or directory
/sw/slc9_x86-64/YODA/yoda-2.1.0-6/include/YODA/highfive/H5Object.hpp:13:10: fatal error: H5Ipublic.h: No such file or directory
make[3]: *** [Makefile:612: libRivetCore_la-Analysis.lo] Error 1
make[3]: *** [Makefile:619: libRivetCore_la-AnalysisLoader.lo] Error 1
make[2]: *** [Makefile:659: all-recursive] Error 1
make[1]: *** [Makefile:567: all-recursive] Error 1
make: *** [Makefile:578: all-recursive] Error 1

Full log here.