chore: refactor golden tests for autopopulation feature #5162

Job	Run time
build(21) except self-service clients	11m 1s
build(8) except for gapic-generator-java	3m 33s
build (11)	12m 1s
build(8) for gapic-generator-java	9m 27s
build (17)	11m 56s
compatibility	1m 34s
gapic-generator-java-bom	1m 43s
showcase (11)	4m 51s
showcase-clirr	3m 5s
showcase (17)	5m 4s
showcase-native	9m 46s
lint	24s
unmanaged_dependency_check	4m 23s
	1h 18m 48s

Provide feedback