Fixed: PostgreSQL 18+ no longer needs the data folder in the volume

[indemidelo]

Change the PostgreSQL data volume path in docker-compose due to changes in PostgreSQL 18+.

Description

In version 18+, PostgreSQL suggests a single mount at /var/lib/postgresql. See also docker-library/postgres#1259

Release note

Fixed: PostgreSQL 18+ no longer needs the data folder in the volume

This PR has:

• been self-reviewed.
  • using the concurrency checklist (Remove this item if the PR doesn't have any relation to concurrency.)
• added documentation for new or modified features or behaviors.
• a release note entry in the PR description.
• added Javadocs for most classes and all non-trivial methods. Linked related entities via Javadoc links.
• added or updated version, license, or notice information in licenses.yaml
• added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader.
• added unit tests or modified existing tests to cover new code paths, ensuring the threshold for code coverage is met.
• added integration tests.
• been tested in a test Druid cluster.