PWGLF: processMC for K0S-phi rapidity correlation studies

[scannito]

• Added process function to compute MC efficiency
• Updated primary pion selection and pion info filling
• Minor fix

[alibuild]

Error while checking build/O2Physics/o2 for 53a8ab2 at 2024-07-26 10:16:

## sw/BUILD/O2Physics-latest/log
/sw/SOURCES/O2Physics/6999-slc7_x86-64/0/PWGLF/Tasks/Strangeness/phik0sanalysis.cxx:302:21: error: no matching function for call to 'o2::framework::HistogramRegistry::add(const char [23], const char [43], o2::framework::HistType, <brace-enclosed initializer list>)'
/sw/SOURCES/O2Physics/6999-slc7_x86-64/0/PWGLF/Tasks/Strangeness/phik0sanalysis.cxx:303:21: error: no matching function for call to 'o2::framework::HistogramRegistry::add(const char [22], const char [51], o2::framework::HistType, <brace-enclosed initializer list>)'
/sw/SOURCES/O2Physics/6999-slc7_x86-64/0/PWGLF/Tasks/Strangeness/phik0sanalysis.cxx:304:21: error: no matching function for call to 'o2::framework::HistogramRegistry::add(const char [23], const char [52], o2::framework::HistType, <brace-enclosed initializer list>)'
/sw/SOURCES/O2Physics/6999-slc7_x86-64/0/PWGLF/Tasks/Strangeness/phik0sanalysis.cxx:325:22: error: no matching function for call to 'o2::framework::HistogramRegistry::add(const char [22], const char [40], o2::framework::HistType, <brace-enclosed initializer list>)'
/sw/SOURCES/O2Physics/6999-slc7_x86-64/0/PWGLF/Tasks/Strangeness/phik0sanalysis.cxx:326:22: error: no matching function for call to 'o2::framework::HistogramRegistry::add(const char [21], const char [48], o2::framework::HistType, <brace-enclosed initializer list>)'
/sw/SOURCES/O2Physics/6999-slc7_x86-64/0/PWGLF/Tasks/Strangeness/phik0sanalysis.cxx:327:22: error: no matching function for call to 'o2::framework::HistogramRegistry::add(const char [22], const char [49], o2::framework::HistType, <brace-enclosed initializer list>)'
ninja: build stopped: subcommand failed.

Full log here.