fix(bqjdbc): avoid reusing statement in DatabaseMetaData #19132

Job	Run time
owlbot-py	1m 32s
gapic-bom	1m 51s
package_name_check	1m 9s
owlbot-yaml	1m 18s
root-pom	1m 48s
group_id_check_for_maps_libraries	9m 9s
gitignore_correctness	1m 7s
generate-readme	1m 12s
	19m 6s

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