chore(opencode): codeq-gcs-upload.yml — drop linux-x64, push-on-main for Mac/Windows

[Kenny-Heitritter]

Closes qBraid/qbraid-infrastructure#295

Issue: gh:qBraid/qbraid-infrastructure#295

Summary

Modify .github/workflows/codeq-gcs-upload.yml to:

• Remove linux-x64 from the OS matrix (Cloud Build owns it from PR 2 onward)
• Add on: push: branches: [main] so Mac/Windows targets auto-fire on every push to fork main
• Keep workflow_dispatch for manual re-runs

Acceptance criteria

• linux-x64 no longer present in the OS matrix of codeq-gcs-upload.yml
• on: workflow_dispatch: augmented by on: push: branches: [main] — push-on-main present; workflow_dispatch stays for manual re-runs
• Mac and Windows targets remain in the matrix
• On the next push to fork main after merge, the workflow fires automatically and produces mac and windows artifacts at their expected GCS destinations (deferred to human verification post-merge)
• PR opened against qBraid/opencode/main containing only this change

Test plan

1. actionlint passes on the modified workflow with no errors.
2. YAML syntax validated with python3 -c "import yaml; yaml.safe_load(...)".
3. Post-merge: push any commit to qBraid/opencode/main and verify the Actions workflow auto-fires for darwin-x64, darwin-arm64, and windows-x64.