[4.2] Fix Audio track crossfade in AnimationPlayer does not work #18594

Job	Run time
📊 Static checks / Code style, file formatting, and docs	34s
🍏 iOS / Template (target=template_release)	13m 35s
🤖 Android / Template (target=template_release)	27m 34s
🐧 Linux / Editor w/ Mono (target=editor)	32m 16s
🐧 Linux / Editor with doubles and GCC sanitizers (target=editor, tests=yes, dev_build=yes, scu_build=yes, precision=double, use_asan=yes, use_ubsan=yes, linker=gold)	35m 18s
🐧 Linux / Editor with clang sanitizers (target=editor, tests=yes, dev_build=yes, use_asan=yes, use_ubsan=yes, use_llvm=yes, linker=lld)	29m 17s
🍎 macOS / Editor (target=editor, tests=yes)	41m 53s
🐧 Linux / Editor with ThreadSanitizer (target=editor, tests=yes, dev_build=yes, use_tsan=yes, use_llvm=yes, linker=lld)	25m 37s
🌐 Web / Template (target=template_release)	18m 23s
🍎 macOS / Template (target=template_release)	16m 6s
🐧 Linux / Template w/ Mono (target=template_release)	22m 39s
🐧 Linux / Minimal template (target=template_release, everything disabled)	13m 15s
🏁 Windows / Editor (target=editor, tests=yes)	39m 59s
🏁 Windows / Template (target=template_release)	27m 53s
🪲 Godot CPP / Build and test Godot CPP	6m 49s
	5h 51m 8s

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