Notify on length when notifying that many-array has changed (#9316) #10576

Job	Run time
lint	1m 16s
test-infra	2m 13s
basic-tests (macos-latest)	6m 32s
basic-tests (windows-latest)	10m 25s
basic-tests (ubuntu-latest)	4m 38s
Chrome on ubuntu-latest	2m 5s
fastboot-tests (macos-latest, fastboot-with-ember-fetch)	1m 39s
Firefox on macos-latest	4m 35s
fastboot-tests (windows-latest, fastboot-with-ember-fetch)	1m 25s
fastboot-tests (ubuntu-latest, fastboot-with-ember-fetch)	1m 22s
additional-scenarios (with-native-fetch)	2m 2s
additional-scenarios (with-ember-fetch-no-jquery)	2m 4s
floating-dependencies	33s
lts (ember-lts-4.4)	2m 17s
additional-scenarios (with-ember-fetch-and-jquery)	1m 57s
Use Node.js 14.x	44s
lts (ember-lts-3.28)	1m 59s
additional-scenarios (with-jquery)	1m 54s
releases	0s
Use Node.js 18.x	58s
external-partners	0s
	50m 38s

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