chore: move bigquery jdbc external test to monorepo #17231

Job	Run time
owlbot-yaml	1m 0s
group_id_check_for_maps_libraries	7m 59s
gapic-bom	2m 1s
gitignore_correctness	1m 2s
generate-readme	1m 30s
root-pom	1m 59s
package_name_check	1m 19s
owlbot-py	1m 14s
	18m 4s

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