feat(gax): Add error attributes to golden signal metrics. #17229

Job	Run time
owlbot-py	1m 12s
root-pom	1m 42s
generate-readme	1m 6s
package_name_check	1m 3s
gitignore_correctness	1m 3s
gapic-bom	1m 51s
owlbot-yaml	1m 2s
group_id_check_for_maps_libraries	7m 50s
	16m 49s

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