V0: use collinear fit from DCAFitter

[f3sch]

For photons the position is better resolved using a specialized collinear method in DCAFitter.
Corresponding change in O2 AliceO2Group/AliceO2#12770

[f3sch]

Linter fails with:

 --Error detail:
PWGLF/DataModel/LFStrangenessTables.h:762: Add #include <vector> for vector<> [build/include_what_you_use] [4]

Since the changes to this file are unrelated to this, should I actually make this change?

[alibuild]

Error while checking build/O2Physics/o2 for add0601 at 2024-03-16 14:26:

## sw/BUILD/O2Physics-latest/log
/sw/SOURCES/O2Physics/5204-slc7_x86-64/0/PWGLF/TableProducer/lambdakzerobuilder.cxx:667:12: error: 'class o2::vertexing::DCAFitterN<2>' has no member named 'setCollinear'
ninja: build stopped: subcommand failed.

Full log here.

[ddobrigk]

@f3sch thanks a lot, this is very nice ! About the possible use cases, I wonder if it would additionally also not be useful to have all V0s (regardless of being TPConly) use this alternate fit path if a certain option is enabled (false by default). This way, conversions could also be studied if both tracks have ITS hits in case of a conversion e.g. in the ITS IB.

One more thing, just out of curiosity: would TPC-TOF matches also fall under your special path? I guess not - it's really just for TPC-only - but I wanted to be sure. Thanks! :-D

[alibuild]

Error while checking build/O2Physics/o2 for 6799384 at 2024-03-17 17:36:

## sw/BUILD/O2Physics-latest/log
/sw/SOURCES/O2Physics/5204-slc7_x86-64/0/PWGLF/TableProducer/lambdakzerobuilder.cxx:667:12: error: 'class o2::vertexing::DCAFitterN<2>' has no member named 'setCollinear'
ninja: build stopped: subcommand failed.

Full log here.

[f3sch]

Hi @ddobrigk, thanks for taking the time. I will implement your suggestion for the additional switch. For now it is TPC-only only :). BTW why does CI fail here or rather I was under the impression that always the new nightly tag would be available but from the build log it seems to be the O2 version is daily-20240312-0130-local?

[alibuild]

Error while checking build/O2Physics/o2 for 28ecd4c at 2024-03-18 08:29:

## sw/BUILD/O2Physics-latest/log
/sw/SOURCES/O2Physics/5204-slc7_x86-64/0/PWGLF/TableProducer/lambdakzerobuilder.cxx:668:12: error: 'class o2::vertexing::DCAFitterN<2>' has no member named 'setCollinear'
ninja: build stopped: subcommand failed.

Full log here.

[f3sch]

@njacazio can this please be merged? cheers