Summary:
Commit 282778fc987c6eeb96eb7e26a518c9cf7d0e7623 incorrectly changes
upstream_repositories.csv commit hash to the wrong commit.  It should
point to a yb-pg15 commit, not the commit being cherry-picked.  Fix the
commit hash.

Test Plan:
Close: #26674
Jenkins: skip

Reviewers: kramanathan, hsunder

Reviewed By: kramanathan, hsunder

Subscribers: yql

Differential Revision: https://phorge.dev.yugabyte.com/D43004