Backport: Simplify pg-upgrade initdb by removing locale parameters

What does this MR do and why?

Describe in detail what merge request is being backported and why

This is the backport of Simplify pg-upgrade initdb by removing locale p... (!9160 - merged)

18.9 introduced PostgreSQL 17, our pg-upgrade fails to upgrade the database, since lc_collate and lc_ctype are removed in PostgreSQL 16 Those settings are per-database.

Related: #9645 (closed)

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• This MR is backporting a bug fix, documentation update, or spec fix, previously merged in the default branch.
• The original MR has been deployed to GitLab.com (not applicable for documentation or spec changes).
• This MR has a severity label assigned (if applicable).

Note to the merge request author and maintainer

If you have questions about the patch release process, please:

• Refer to the patch release runbook for engineers and maintainers for guidance.
• Ask questions on the #releases Slack channel (internal only).