feat(gax): Add error attributes to golden signal metrics. #18657

Job	Run time
enforcer	19m 10s
lint	3m 11s
changes	3s
windows	2m 31s
bulk-filter	1m 2s
generation-config-check	1m 51s
gapic-libraries-bom	18m 13s
split-units (sdk-platform-java, 8)	4m 12s
split-units (sdk-platform-java, 21)	5m 18s
split-units (sdk-platform-java, 17)	4m 24s
split-units (sdk-platform-java, 25)	4m 37s
split-units (sdk-platform-java, 11)	5m 37s
units (8)	43m 36s
units (21)	32m 45s
units (11)	43m 19s
units (25)	35m 0s
units (17)	33m 45s
	4h 18m 34s

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