Add missing `working-directory` in scheduled.yml #1825

Job	Run time
Build	49m 1s
Spark Aggregate Fuzzer	16m 2s
Spark Fuzzer	15m 40s
Presto Bias Fuzzer	0s
Presto Fuzzer	15m 45s
Aggregate Fuzzer	16m 11s
Exchange Fuzzer	16m 22s
Join Fuzzer	15m 46s
Aggregation Fuzzer with Presto as source of truth	0s
Signature Changes	4s
Spark Bias Fuzzer	0s
	2h 24m 51s

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