ci: restore sdk-platform-java jobs #17763

Job	Run time
gitignore_correctness	1m 6s
generate-readme	1m 8s
owlbot-yaml	1m 4s
owlbot-py	1m 14s
group_id_check_for_maps_libraries	8m 8s
gapic-bom	1m 47s
root-pom	1m 45s
package_name_check	1m 5s
	17m 17s

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