fix(SubnavigationBar): ignore falsy children #3477

Job	Run time
Run linters	1m 20s
Detect what files changed	5s
Call reusable workflow / Run unit tests	1m 43s
Upload docs dist artifact (styleguide)	2m 3s
Upload docs dist artifact (storybook)	1m 2s
Analyze bundle size	2m 11s
Call reusable workflow / Run e2e tests for (shard 1/10)	2m 47s
Call reusable workflow / Run e2e tests for (shard 2/10)	3m 17s
Call reusable workflow / Run e2e tests for (shard 3/10)	2m 47s
Call reusable workflow / Run e2e tests for (shard 4/10)	2m 56s
Call reusable workflow / Run e2e tests for (shard 5/10)	3m 33s
Call reusable workflow / Run e2e tests for (shard 6/10)	2m 42s
Call reusable workflow / Run e2e tests for (shard 7/10)	3m 18s
Call reusable workflow / Run e2e tests for (shard 8/10)	2m 44s
Call reusable workflow / Run e2e tests for (shard 9/10)	2m 44s
Call reusable workflow / Run e2e tests for (shard 10/10)	3m 18s
Report unit test results	3s
Prepare and upload e2e's HTML report artifact	30s
Call reusable workflow / Upload PR workflow payload artifact	5s
Call reusable workflow / Download PR workflow payload artifact	0s
	39m 8s

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