Docs: Update parameter type hints to include null for thumbnail-relat… #12858

Job	Run time
Core running from build / Core running from build / Linux	2m 5s
Core running from src / Core running from src / Linux	2m 1s
Core running from build / Core running from build / Windows	4m 11s
Core running from src / Core running from src / Windows	4m 6s
Core running from build / Core running from build / MacOS	2m 16s
Core running from src / Core running from src / MacOS	1m 50s
Gutenberg running from build / Gutenberg running from build / Linux	9m 7s
Gutenberg running from src / Gutenberg running from src / Linux	8m 46s
Gutenberg running from build / Gutenberg running from build / Windows	13m 11s
Gutenberg running from src / Gutenberg running from src / Windows	13m 3s
Gutenberg running from build / Gutenberg running from build / MacOS	7m 42s
Gutenberg running from src / Gutenberg running from src / MacOS	10m 3s
Slack Notifications	0s
Failed workflow tasks	0s
	1h 18m 21s

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