build: add monorepo issue migration script #16260

Job	Run time
root-pom	1m 28s
gapic-bom	1m 42s
generate-readme	1m 3s
owlbot-yaml	57s
owlbot-py	1m 6s
package_name_check	57s
gitignore_correctness	53s
group_id_check_for_maps_libraries	6m 57s
	15m 3s

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