Fix postgres script permissions

[hajnalmt]

The initdb.sh and the upgrade.sh scripts in the postgres image were not owned by the postgres user, which made them failing with permission denied errors in some local builds.

Comprehensive Summary of your change

Adding the scripts to the appropriate user and fixing the permissions resolved the issue.

Issue being fixed

Fixes #21006 Please indicate you've done the following:

• [X] Well Written Title and Summary of the PR
• [x] Label the PR as needed. "release-note/ignore-for-release, release-note/new-feature, release-note/update, release-note/enhancement, release-note/community, release-note/breaking-change, release-note/docs, release-note/infra, release-note/deprecation"
• [X] Accepted the DCO. Commits without the DCO will delay acceptance.
• [x] Made sure tests are passing and test coverage is added if needed.
• [X] Considered the docs impact and opened a new docs issue or PR with docs changes if needed in website repository.