[RF] Fixes and performance improvements for `RooAbsArg::getParameters()` #22857

Job	Run time
Windows 10 x64 Release	9m 29s
Windows 10 x86 Release	1h 0m 27s
mac-beta ARM64 CMAKE_CXX_STANDARD=23	45m 15s
mac13 ARM64 builtin_zlib=ON	27m 4s
mac14 X64 CMAKE_CXX_STANDARD=20	1s
Upload Event Payload	3s
fedora42 CMAKE_CXX_STANDARD=23	38m 28s
mac15 ARM64 CMAKE_CXX_STANDARD=23	25m 57s
alma9 CMAKE_BUILD_TYPE=Debug	1h 8m 19s
ubuntu2404 CMAKE_BUILD_TYPE=Debug	1h 8m 19s
ubuntu22 imt=Off, CMAKE_BUILD_TYPE=Debug	1h 8m 20s
alma8	36m 8s
fedora43 CMAKE_CXX_STANDARD=23	33m 4s
alma10 clang Ninja CMAKE_C_COMPILER=clang, CMAKE_CXX_COMPILER=clang++	30m 1s
ubuntu2504 CMAKE_CXX_STANDARD=23	38m 17s
rawhide Fedora pydebug CMAKE_CXX_STANDARD=23	38m 17s
ubuntu2510 CMAKE_CXX_STANDARD=23	36m 55s
alma9 modules_off runtime_cxxmodules=Off	28m 48s
debian125 CMAKE_CXX_STANDARD=20, dev=ON, CMAKE_CXX_FLAGS=-Wsuggest-override	35m 35s
alma9 march_native CMAKE_BUILD_TYPE=RelWithDebInfo, CMAKE_CXX_FLAGS=-march=native, CMAKE_C_FLAGS=-march=native, builtin_zlib=ON, builtin_zstd=ON	32m 19s
alma10	30m 54s
alma9 arm64 CMAKE_BUILD_TYPE=RelWithDebInfo, builtin_zlib=ON, builtin_zstd=ON	50m 31s
	13h 22m 31s

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