Build/Test Tools: Fix group for `wp_unique_prefixed_id()` tests. #14014

Job	Run time
QUnit Tests	2m 53s
Slack Notifications / Prepare notifications	6s
Slack Notifications / Success notifications	5s
Slack Notifications / Failure notifications	0s
Slack Notifications / Cancelled notifications	0s
Slack Notifications / Fixed notifications	0s
Failed workflow tasks	0s
	3m 4s

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