Add many_materials stress test #56010

Job	Run time
build (windows-latest)	15m 38s
check-doc	12m 51s
check-bevy-internal-imports	4s
check-missing-examples-in-docs	34s
ci	4m 58s
miri	11m 39s
run-examples-macos-metal	6m 3s
build (ubuntu-latest)	7m 49s
toml	2m 0s
build (macos-latest)	6m 36s
typos	5s
check-missing-features-in-docs	31s
markdownlint	1m 5s
check-compiles	7m 33s
check-compiles-no-std	2m 8s
build-wasm-atomics	1m 58s
build-wasm	1m 44s
msrv	1m 45s
	1h 25m 1s

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