Rework animation to be done in two phases. #36821

Job	Run time
build (windows-latest)	7m 16s
check-bevy-internal-imports	5s
build (ubuntu-latest)	3m 51s
build (macos-latest)	3m 57s
check-doc	7m 47s
check-missing-examples-in-docs	41s
ci	3m 10s
miri	7m 29s
run-examples-on-windows-dx12	14m 4s
toml	6s
check-missing-features-in-docs	30s
markdownlint	1m 21s
check-compiles	4m 12s
msrv	1m 27s
build-wasm	1m 44s
	57m 40s

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