[PWGDQ] Save the information of ambiguous pairs

[yuanz-USTC]

Define histograms to save the information of mix event ambiguous pairs and also ambiguous pairs which are double counted for both same event and mix event.

[alibuild]

Error while checking build/O2Physics/o2 for 8d48489 at 2025-04-02 16:24:

## sw/BUILD/O2Physics-latest/log
/sw/SOURCES/O2Physics/10733-slc9_x86-64/0/PWGDQ/Tasks/tableReader_withAssoc.cxx:1762:37: error: 'iPairs' was not declared in this scope; did you mean 'iPair'?
/sw/SOURCES/O2Physics/10733-slc9_x86-64/0/PWGDQ/Tasks/tableReader_withAssoc.cxx:1765:35: error: 'iPairs' was not declared in this scope; did you mean 'iPair'?
/sw/SOURCES/O2Physics/10733-slc9_x86-64/0/PWGDQ/Tasks/tableReader_withAssoc.cxx:1957:35: error: 'iPairs' was not declared in this scope; did you mean 'iPair'?
/sw/SOURCES/O2Physics/10733-slc9_x86-64/0/PWGDQ/Tasks/tableReader_withAssoc.cxx:1960:33: error: 'iPairs' was not declared in this scope; did you mean 'iPair'?
ninja: build stopped: subcommand failed.

Full log here.

[alibuild]

Error while checking build/O2Physics/o2 for bd3a358 at 2025-04-28 15:09:

No log files found

Full log here.