Rewrite CompletableFutureExtension.allSettled to not use CompletableF… #552

Job	Run time
release-notes	6s
build-libraries / build	13m 4s
build-examples / build	4m 32s
federation-integration / compatibility	4m 15s
federation-integration / composition	3m 11s
graalvm-integration / graalvm-integration (ktor-graalvm-server)	13m 20s
graalvm-integration / graalvm-integration (maven-graalvm-server)	9m 48s
http-spec-compliance / http-spec-compliance (spring-server)	3m 2s
plugin-integration / android-test	4m 19s
graalvm-integration / graalvm-integration (spring-graalvm-server)	13m 14s
http-spec-compliance / http-spec-compliance (ktor-server)	2m 2s
plugin-integration / gradle-integration-tests	6m 7s
plugin-integration / maven-integration-tests	6m 20s
	1h 23m 20s

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