feat(gax): Add error attributes to golden signal metrics. #17260

Job	Run time
gapic-bom	1m 48s
package_name_check	1m 8s
gitignore_correctness	1m 2s
owlbot-py	1m 15s
root-pom	1m 40s
generate-readme	1m 15s
owlbot-yaml	1m 2s
group_id_check_for_maps_libraries	8m 3s
	17m 13s

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