chore: move bigquery jdbc external test to monorepo #17239

Job	Run time
owlbot-py	1m 24s
root-pom	1m 44s
gitignore_correctness	1m 20s
gapic-bom	1m 54s
generate-readme	59s
package_name_check	1m 16s
owlbot-yaml	1m 18s
group_id_check_for_maps_libraries	8m 27s
	18m 22s

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