Remove unused `NOTIFICATION_NODE_RECACHE_REQUESTED` notification #415

Job	Run time
📊 Static checks / Code style, file formatting, and docs	2m 43s
🤖 Android / Template (target=template_release)	3m 29s
🍎 macOS / Editor (target=editor, tests=yes)	4m 48s
🐧 Linux / Editor w/ Mono (target=editor)	5m 20s
🍎 macOS / Template (target=template_release)	29m 59s
🍏 iOS / Template (target=template_release)	17m 39s
🐧 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)	17m 14s
🌐 Web / Template (target=template_release)	19m 55s
🐧 Linux / Editor with clang sanitizers (target=editor, tests=yes, dev_build=yes, use_asan=yes, use_ubsan=yes, use_llvm=yes, linker=lld)	6m 28s
🐧 Linux / Editor with ThreadSanitizer (target=editor, tests=yes, dev_build=yes, use_tsan=yes, use_llvm=yes, linker=lld)	11m 9s
🏁 Windows / Editor (target=editor, tests=yes)	8m 23s
🐧 Linux / Template w/ Mono (target=template_release)	34m 50s
🏁 Windows / Template (target=template_release)	12m 9s
🐧 Linux / Minimal template (target=template_release, everything disabled)	24m 0s
🪲 Godot CPP / Build and test Godot CPP	10m 7s
	3h 28m 13s

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