feat(spanner): add option for auto-tagging transactions #19084

Job	Run time
group_id_check_for_maps_libraries	9m 13s
root-pom	1m 50s
owlbot-yaml	1m 8s
package_name_check	1m 8s
owlbot-py	1m 17s
gapic-bom	1m 46s
gitignore_correctness	1m 7s
generate-readme	1m 20s
	18m 49s

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