databases/postgresql17-*: Upgrade to RC1

Several bug fixes were applied for PostgreSQL 17 during the Beta 3
period. These include:

• Revert the MERGE/SPLIT partition feature.

• Fix for feature that improves performance around logical decoding of subtransactions. For a detailed list of fixes, please visit the open items [1] page.

[1]: https://wiki.postgresql.org/wiki/PostgreSQL_17_Open_Items#resolved_before_17rc1

Release notes: https://www.postgresql.org/about/news/postgresql-17-rc1-released-2926/