[PWGUD] Shrink 8 flag variables to one variable

[amatyja]

Shrink 8 flag variables to one variable
Corrected code-check errors
Changed order of selection cuts

[github-actions]

O2 linter results: ❌ 2 errors, ⚠️ 0 warnings, 🔕 0 disabled

[alibuild]

Error while checking build/O2Physics/staging for 435696b at 2026-08-26 14:07:

## sw/BUILD/O2Physics-latest/log
/sw/SOURCES/O2Physics/slc9_x86-64-slc9_x86-64/0/PWGUD/TableProducer/tauThreeProngEventTableProducer.cxx:811:17: error: statement has no effect [-Werror=unused-value]
/sw/SOURCES/O2Physics/slc9_x86-64-slc9_x86-64/0/PWGUD/TableProducer/tauThreeProngEventTableProducer.cxx:1157:51: error: for increment expression has no effect [-Werror=unused-value]
/sw/SOURCES/O2Physics/slc9_x86-64-slc9_x86-64/0/PWGUD/TableProducer/tauThreeProngEventTableProducer.cxx:1411:23: error: statement has no effect [-Werror=unused-value]
ninja: build stopped: subcommand failed.

Full log here.