chore: restore nightly protobuf compatibility check #4758

Job	Run time
filter	1m 10s
downstream-compatibility (java-firestore)	3m 54s
downstream-compatibility (java-bigtable)	8m 1s
downstream-compatibility (java-pubsub)	4m 27s
downstream-compatibility (spring-cloud-gcp)	12m 37s
conditional-required-check	3s
	30m 12s

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