Tests: Add unit test for empty comment tags in export #22798

Job	Run time
Core running from src / Linux	2m 23s
Core running from build / Windows	3m 58s
Core running from build / MacOS	2m 3s
Core running from src / Windows	4m 30s
Core running from build / Linux	2m 30s
Core running from src / MacOS	4m 20s
Gutenberg running from build / Linux	9m 0s
Gutenberg running from src / Linux	9m 4s
Gutenberg running from src / Windows	15m 41s
Gutenberg running from src / MacOS	12m 44s
Gutenberg running from build / MacOS	14m 24s
Gutenberg running from build / Windows	15m 22s
Slack Notifications	0s
Failed workflow tasks	0s
	1h 35m 59s

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