[PWGDQ] Fix e-mu mixed-event histograms

[Shunsuke-Kurita]

Fix e-mu mixed-event histograms being silently empty in tableReader_withAssoc fTrackMuonHistNames was stored before the mixing histogram names were appended, so PairsEleMuME* classes were never filled. Store the names after the ME block, matching the ordering already used in dqEfficiency_withAssoc.

[github-actions]

O2 linter results: ❌ 182 errors, ⚠️ 83 warnings, 🔕 9 disabled

[alibuild]

Error while checking build/O2Physics/code-check for b9e5808 at 2026-07-06 09:26:

## sw/BUILD/O2Physics-code-check-latest/log
--
========== List of issues found ==========
++ echo 'Found 12 errors and 0 warnings.'
Found 12 errors and 0 warnings.
++ [[ 12 -gt 0 ]]
++ cat /sw/BUILD/87bfab8a1a37987b5fa18e6b8d5fa3f2a9149f6e/O2Physics-code-check/errors.txt
PWGDQ/Tasks/tableReader_withAssoc.cxx:53:1: error: included header TH3.h is not used directly [misc-include-cleaner,-warnings-as-errors]
PWGDQ/Tasks/tableReader_withAssoc.cxx:705:30: error: do not use static_cast to downcast from a base to a derived class; use dynamic_cast instead [cppcoreguidelines-pro-type-static-cast-downcast,-warnings-as-errors]
PWGDQ/Tasks/tableReader_withAssoc.cxx:956:29: error: do not use static_cast to downcast from a base to a derived class; use dynamic_cast instead [cppcoreguidelines-pro-type-static-cast-downcast,-warnings-as-errors]
PWGDQ/Tasks/tableReader_withAssoc.cxx:1888:5: error: use auto when initializing with a cast to avoid duplicating the type name [modernize-use-auto,-warnings-as-errors]
PWGDQ/Tasks/tableReader_withAssoc.cxx:3209:29: error: do not use static_cast to downcast from a base to a derived class; use dynamic_cast instead [cppcoreguidelines-pro-type-static-cast-downcast,-warnings-as-errors]
PWGDQ/Tasks/tableReader_withAssoc.cxx:3500:9: error: use auto when initializing with a cast to avoid duplicating the type name [modernize-use-auto,-warnings-as-errors]
PWGDQ/Tasks/tableReader_withAssoc.cxx:3501:9: error: use auto when initializing with a cast to avoid duplicating the type name [modernize-use-auto,-warnings-as-errors]
PWGDQ/Tasks/tableReader_withAssoc.cxx:3700:5: error: use auto when initializing with a cast to avoid duplicating the type name [modernize-use-auto,-warnings-as-errors]
PWGDQ/Tasks/tableReader_withAssoc.cxx:3701:5: error: use auto when initializing with a cast to avoid duplicating the type name [modernize-use-auto,-warnings-as-errors]
PWGDQ/Tasks/tableReader_withAssoc.cxx:4182:5: error: use auto when initializing with a template cast to avoid duplicating the type name [modernize-use-auto,-warnings-as-errors]
PWGDQ/Tasks/tableReader_withAssoc.cxx:4551:19: error: implicit conversion 'uint32_t' (aka 'unsigned int') -> 'bool' [readability-implicit-bool-conversion,-warnings-as-errors]
PWGDQ/Tasks/tableReader_withAssoc.cxx:4599:19: error: implicit conversion 'uint32_t' (aka 'unsigned int') -> 'bool' [readability-implicit-bool-conversion,-warnings-as-errors]
++ [[ 0 -gt 0 ]]
++ [[ 12 -gt 0 ]]
++ exit 1
--

Full log here.