[PWGDQ] add varmaps for MC in A2

[ypwangg]

No description provided.

[github-actions]

O2 linter results: ❌ 2 errors, ⚠️ 20 warnings, 🔕 0 disabled

[alibuild]

Error while checking build/O2Physics/code-check for 4c79003 at 2026-09-02 05:17:

## sw/BUILD/O2Physics-code-check-latest/log
--
========== List of issues found ==========
++ echo 'Found 2 errors and 8 warnings.'
Found 2 errors and 8 warnings.
++ [[ 2 -gt 0 ]]
++ cat /sw/BUILD/adffc49a6f7dd6d991a3b2230aa30482bac5e3fb/O2Physics-code-check/errors.txt
PWGDQ/Core/VarManager.cxx:146:14: error: do not implicitly decay an array into a pointer; consider using gsl::array_view or an explicit cast instead [cppcoreguidelines-pro-bounds-array-to-pointer-decay,-warnings-as-errors]
PWGDQ/Core/VarManager.cxx:415:14: error: do not implicitly decay an array into a pointer; consider using gsl::array_view or an explicit cast instead [cppcoreguidelines-pro-bounds-array-to-pointer-decay,-warnings-as-errors]
++ [[ 8 -gt 0 ]]
++ cat /sw/BUILD/adffc49a6f7dd6d991a3b2230aa30482bac5e3fb/O2Physics-code-check/warnings.txt
PWGDQ/Core/VarManager.cxx:51:1: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays]
PWGDQ/Core/VarManager.cxx:52:1: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays]
PWGDQ/Core/VarManager.cxx:54:1: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays]
PWGDQ/Core/VarManager.cxx:66:1: warning: do not declare C-style arrays, use 'std::array' instead [modernize-avoid-c-arrays]
PWGDQ/Core/VarManager.cxx:92:28: warning: initializer for base class 'TObject' is redundant [readability-redundant-member-init]
PWGDQ/Core/VarManager.cxx:308:5: warning: do not use 'else' after 'return' [readability-else-after-return]
PWGDQ/Core/VarManager.cxx:482:5: warning: do not use 'else' after 'return' [readability-else-after-return]
PWGDQ/Core/VarManager.h:1605:15: warning: function 'VarManager::SetPhiMap' has a definition with different parameter names [readability-inconsistent-declaration-parameter-name]
++ [[ 2 -gt 0 ]]
++ exit 1
--

Full log here.