ci, emulator: use `actions/checkout` to install V and examples in one… #542

Job	Run time
build-v-examples-as-apk-and-aab (ubuntu-20.04, 11, 31)	6m 21s
build-v-examples-with-gc-disabled (ubuntu-20.04, 11, 31)	4m 41s
build-v-examples-as-apk-and-aab (ubuntu-20.04, 11, 33)	6m 12s
build-legacy-v-examples-as-apk-and-aab (ubuntu-20.04, 8, 31)	6m 49s
build-v-examples-with-gc-disabled (ubuntu-20.04, 11, 33)	4m 50s
build-v-examples-as-apk-and-aab (ubuntu-20.04, 15, 31)	6m 13s
build-legacy-v-examples-as-apk-and-aab (ubuntu-20.04, 8, 33)	8m 6s
build-v-examples-with-gc-disabled (ubuntu-20.04, 15, 31)	4m 48s
build-v-examples-as-apk-and-aab (ubuntu-20.04, 15, 33)	6m 6s
build-v-examples-as-apk-and-aab (ubuntu-20.04, 20, 31)	5m 53s
build-v-examples-with-gc-disabled (ubuntu-20.04, 15, 33)	4m 50s
build-v-examples-as-apk-and-aab (ubuntu-20.04, 20, 33)	5m 51s
build-v-examples-with-gc-disabled (ubuntu-20.04, 20, 31)	4m 47s
build-v-examples-with-gc-disabled (ubuntu-20.04, 20, 33)	4m 44s
	1h 20m 11s

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