feat: autopopulate fields in the request #5012

Job	Run time
build (11)	12m 11s
build (17)	11m 50s
build(21) except self-service clients	10m 55s
build(8) except for gapic-generator-java	3m 23s
build(8) for gapic-generator-java	9m 9s
compatibility	1m 14s
gapic-generator-java-bom	1m 33s
lint	30s
showcase (11)	4m 46s
showcase-clirr	2m 56s
showcase-native	9m 25s
unmanaged_dependency_check	3m 47s
showcase (17)	4m 50s
	1h 16m 29s

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