Fixed test_decayfinder for undefined behavior

This test is using heavily cppyy, but ownership and scoping of C++ object is inexistent there, leading to undefined behavior The fix is as horrible as the code : make all local variables global to be sure nothing is deleted which should not be. This test should probaby be rewritten in plain C++

added lhcb-lcg-dev4lhcb label

/ci-test --no-downstream

/ci-test --without-downstream

resolved all threads

added ci-test-triggered label

added RTA label

• [2025-02-05 16:02] Validation started with lhcb-master-mr#12461
• [2025-02-05 16:46] Validation started with lhcb-lcg-dev4lhcb#509
• [2025-02-05 18:29] Automatic merge failed in [lhcb-master-mr#12466](https://lhcb-nightlies.web.cern.ch/nightly/lhcb-master-mr/12466/Rec/checkout
• [2025-02-05 19:50] Validation started with lhcb-master-mr#12468
• [2025-02-06 09:50] Validation started with lhcb-master-mr#12472
• [2025-02-06 10:31] Validation started with lhcb-lcg-dev4lhcb#510
• [2025-02-07 09:50] Validation started with lhcb-lcg-dev4lhcb#511

added 5 commits

• 6b441838...c8e88bf3 - 4 commits from branch master
• 232260d2 - Fixed test_decayfinder for undefined behavior

Compare with previous version

added 3 commits

• 232260d2...d54a3bbf - 2 commits from branch master
• 32de6c9e - Fixed test_decayfinder for undefined behavior

Compare with previous version

resolved all threads

/ci-test --without-downstream

/ci-test --without-downstream

resolved all threads

mentioned in issue Moore#910 (closed)

resolved all threads

merged

mentioned in commit ad73d4ca