[PWGEM] Differentiate b2cc2e_b2c2e and b2cc2e_b2cc2e into life time

[feisenhu]

Look more differential into the b2cc2e_b2c2e and b2cc2e_b2cc2e signals.
Separate them by the life time of the charmed Hadrons which are the mother of the lepton/electron.

[alibuild]

Error while checking build/O2Physics/o2 for d044a6b at 2026-02-14 17:31:

## sw/BUILD/O2Physics-latest/log
/sw/SOURCES/O2Physics/14973-slc9_x86-64/0/PWGEM/Dilepton/Tasks/checkMCPairTemplate.cxx:467:39: error: unused variable 'anti_beauty_mesons' [-Werror=unused-variable]
/sw/SOURCES/O2Physics/14973-slc9_x86-64/0/PWGEM/Dilepton/Tasks/checkMCPairTemplate.cxx:468:15: error: unused variable 'nm_b' [-Werror=unused-variable]
/sw/SOURCES/O2Physics/14973-slc9_x86-64/0/PWGEM/Dilepton/Tasks/checkMCPairTemplate.cxx:470:39: error: unused variable 'anti_beauty_baryons' [-Werror=unused-variable]
/sw/SOURCES/O2Physics/14973-slc9_x86-64/0/PWGEM/Dilepton/Tasks/checkMCPairTemplate.cxx:471:15: error: unused variable 'nb_b' [-Werror=unused-variable]
/sw/SOURCES/O2Physics/14973-slc9_x86-64/0/PWGEM/Dilepton/Tasks/checkMCPairTemplate.cxx:472:39: error: unused variable 'sum_beauty_mesons' [-Werror=unused-variable]
/sw/SOURCES/O2Physics/14973-slc9_x86-64/0/PWGEM/Dilepton/Tasks/checkMCPairTemplate.cxx:473:39: error: unused variable 'sum_beauty_baryons' [-Werror=unused-variable]
ninja: build stopped: subcommand failed.

Full log here.

[alibuild]

Auto-approving on behalf of @feisenhu.