Monitoring-user password logged in cleartext by postgres_exporter in postgresql VM charm

The postgresql-operator charm runs a Prometheus postgres_exporter to collect database metrics using a dedicated "monitoring" PostgreSQL user. On database connection errors, the exporter writes the monitoring user's password in cleartext to its logs. Any actor able to read those logs can recover the password, which grants read-only pg_monitor access to PostgreSQL. This is fixed in the dev track (14/edge) in revisions 1189 (arm64) and 1190 (amd64), and in the stable track (14/stable) in revisions 1216 (arm64) and 1217 (amd64).