Return a boolean from `set_if_neq` #29745

Job	Run time
build (windows-latest)	11m 58s
build (ubuntu-latest)	5m 7s
build (macos-latest)	5m 44s
check-bevy-internal-imports	5s
check-doc	13m 53s
check-missing-examples-in-docs	45s
ci	4m 45s
miri	7m 46s
run-examples-on-windows-dx12	19m 7s
check-missing-features-in-docs	50s
markdownlint	1m 22s
check-compiles	4m 26s
msrv	1m 44s
build-wasm	4m 32s
	1h 22m 4s

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