Make the theme and plugin file editors more consistent #12377

Job	Run time
Core running from build / Core running from build / Linux	2m 2s
Core running from src / Core running from src / Linux	1m 56s
Core running from build / Core running from build / Windows	4m 1s
Core running from src / Core running from src / Windows	4m 37s
Core running from build / Core running from build / MacOS	3m 10s
Core running from src / Core running from src / MacOS	1m 40s
Gutenberg running from build / Gutenberg running from build / Linux	8m 48s
Gutenberg running from build / Gutenberg running from build / Windows	12m 25s
Gutenberg running from src / Gutenberg running from src / Linux	8m 31s
Gutenberg running from build / Gutenberg running from build / MacOS	9m 37s
Gutenberg running from src / Gutenberg running from src / MacOS	9m 50s
Gutenberg running from src / Gutenberg running from src / Windows	12m 2s
Slack Notifications	0s
Failed workflow tasks	0s
	1h 18m 39s

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