Cannot use 'verify-full' when using an external PostgreSQL Database with Red Hat Single Sign-On (RH SSO) deployed in Red Hat OpenShift Container Platform (OCP)

Issue

With the RH SSO in OCP, we cannot activate the verify-full TLS policy when using an external PostgreSQL, receiving the following error:

[0m[33m20:07:52,359 WARN  [org.jboss.jca.core.connectionmanager.pool.strategy.OnePool] (MSC service thread 1-2) IJ000604: Throwable while attempting to get a new connection: null: javax.resource.ResourceException: IJ031084: Unable to create connection
  at ...
Caused by: org.postgresql.util.PSQLException: The hostname keycloak-postgresql.<NAMESPACE>.svc.cluster.local could not be verified.
  at org.postgresql@42.2.3//org.postgresql.ssl.MakeSSL.convert(MakeSSL.java:93)
  at org.postgresql@42.2.3//org.postgresql.core.v3.ConnectionFactoryImpl.enableSSL(ConnectionFactoryImpl.java:384)
  at org.postgresql@42.2.3//org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:156)
  at org.postgresql@42.2.3//org.postgresql.core.ConnectionFactory.openConnection(ConnectionFactory.java:49)
  at org.postgresql@42.2.3//org.postgresql.jdbc.PgConnection.<init>(PgConnection.java:201)
  at org.postgresql@42.2.3//org.postgresql.Driver.makeConnection(Driver.java:454)
  at org.postgresql@42.2.3//org.postgresql.Driver.connect(Driver.java:256)