Although pax-jdbc-pool-dbcp2 feature is one of the most popular jbdc connection pools comes with karaf, however org.ops4j.pax.jdbc/pax-jdbc-pool-dbcp2/1.3.0 artifact is not included.

This is a knowledge article to recommend pax-jdbc-pool-dbcp2, and it's much better to add the artifact to a karaf container by default.
https://access.redhat.com/solutions/4008751(https://access.redhat.com/solutions/4008751)