fix beta & canary tests (#2571) #5799

Job	Run time
Build extensions	1m 20s
Test	2m 4s
ember-try (ember-lts-3.16)	1m 11s
ember-try (ember-lts-3.20)	1m 24s
ember-try (ember-lts-3.24)	1m 24s
ember-try (ember-lts-3.28)	1m 14s
ember-try (ember-release)	1m 33s
ember-try (ember-beta)	1m 37s
ember-try (ember-canary)	1m 15s
ember-try (ember-default-no-prototype-extensions)	1m 6s
Publish Firefox extension	57s
Publish Chrome extension	6s
Publish bookmarklet	0s
Publish npm package	5s
	15m 16s

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