Upgrading pgsql to v17 with GitLab EE 18.9.1 errors out - "lc_ctype"

When attempting an early-bird pgsql upgrade to v17, the update command errors out.

git swinter # gitlab-ctl pg-upgrade -V 17
Checking for an omnibus managed postgresql: OK
Checking if postgresql['version'] is set: OK
Checking if we already upgraded: NOT OK
Checking for a newer version of PostgreSQL to install: OK
Upgrading PostgreSQL to 17.7
Checking for previous failed upgrade attempts: NOT OK
Checking if disk for directory /var/opt/gitlab/postgresql/data has enough free space for PostgreSQL upgrade: OK
Checking if PostgreSQL bin files are symlinked to the expected location: OK
Waiting 30 seconds to ensure tasks complete before PostgreSQL upgrade.
See https://docs.gitlab.com/omnibus/settings/database.html#upgrade-packaged-postgresql-server for details
If you do not want to upgrade the PostgreSQL server at this time, enter Ctrl-C and see the documentation for details

Please hit Ctrl-C now if you want to cancel the operation.
Toggling deploy page:cp /opt/gitlab/embedded/service/gitlab-rails/public/deploy.html /opt/gitlab/embedded/service/gitlab-rails/public/index.html
Toggling deploy page: OK
Toggling services:ok: down: alertmanager: 0s, normally up
ok: down: gitaly: 0s, normally up
ok: down: gitlab-exporter: 0s, normally up
ok: down: gitlab-kas: 0s, normally up
ok: down: logrotate: 1s, normally up
ok: down: mailroom: 0s, normally up
ok: down: node-exporter: 1s, normally up
ok: down: postgres-exporter: 0s, normally up
ok: down: redis-exporter: 1s, normally up
ok: down: registry: 0s, normally up
ok: down: sidekiq: 0s, normally up
Toggling services: OK
There was an error fetching locale and encoding information from the database
Please ensure the database is running and functional before running pg-upgrade
STDOUT: 
STDERR: ERROR:  unrecognized configuration parameter "lc_ctype"
== Fatal error ==
Please check error logs
== Reverting ==