new: otp-2628: update postgres docker to 15

Closes otp-2628

Summary by CodeRabbit

• New Features
  • Updated OTP database ownership management for improved security.
  • Upgraded integration test database image to a more recent version for enhanced performance.
• Bug Fixes
  • Corrected database ownership command to ensure proper access control.
• Chores
  • Updated Docker base image to the latest version for better compatibility and support.