Fix code_freeze lane committing beta bump to wrong branch

[iangmaia]

Relates to AINFRA-2108

Summary

• Move create_backmerge_pr after new_beta_release in the code_freeze lane to fix the beta version bump being committed to the backmerge branch instead of the release branch

Root cause

The create_release_backmerge_pull_request action (from release-toolkit) creates a merge/release-X.Y.Z-into-trunk intermediate branch and leaves git HEAD checked out on it. When new_beta_release subsequently runs bump_version_commit_and_push, it commits the version bump to the backmerge branch instead of the release branch.

The triggered build correctly targets release/X.Y.Z, but that branch never receives the beta bump commit, so it builds the wrong version.

Fix

Move create_backmerge_pr to after new_beta_release in code_freeze. The backmerge action's branch switch no longer matters since it happens after the beta bump and build trigger.

Pre-merge Checklist

• Changes are tested locally

🤖 Generated with Claude Code

[sejas]

The code looks good to me. The build version should be beta now, instead of the previous version.