tests: Add retry metrics tests to ITOtelGoldenMetrics #678

Job	Run time
filter	1m 4s
build(8) except for gapic-generator-java	4m 6s
build(8) for gapic-generator-java	11m 44s
build(25) except self-service clients	12m 8s
build(21) except self-service clients	12m 26s
build(8) for showcase	9m 49s
unmanaged_dependency_check	8m 12s
showcase (11)	10m 46s
showcase (17)	10m 49s
showcase-clirr	5m 12s
build (17)	13m 40s
dependency_analyzer_unit_test	1m 21s
build (11)	13m 51s
gapic-generator-java-bom	2m 1s
showcase (25)	10m 21s
showcase (21)	10m 5s
	2h 17m 35s

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