chore(main): release 1.70.0 #15240

Job	Run time
owlbot-yaml	46s
generate-readme	49s
group_id_check_for_maps_libraries	6m 46s
package_name_check	47s
root-pom	1m 25s
owlbot-py	46s
gitignore_correctness	48s
gapic-bom	1m 26s
	13m 33s

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