build: update monorepo-migration scripts #16638

Job	Run time
gitignore_correctness	57s
gapic-bom	1m 32s
generate-readme	1m 5s
group_id_check_for_maps_libraries	6m 43s
owlbot-py	1m 8s
root-pom	1m 34s
owlbot-yaml	59s
package_name_check	1m 0s
	14m 58s

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