fix(test): stabilize flaky SpanEvidencePreview spec #248356

Job	Run time
detect what files changed	14s
api url typescript generation	0s
backend typing	0s
requirements check	0s
cli test	0s
api docs test	0s
check migration	0s
backend migration tests	0s
select tests	0s
monolith-dbs test	0s
calculate test shards	-1s
Backend	3s
backend test	-1s
	15s

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