revert: remove repository sync Actions workflow

[xnoto]

Summary

• remove the custom repository-sync GitHub Actions workflow and its templates

Reason

Repository sync must be performed by the tfroot-github OpenTofu apply using GitHub provider branch, repository-file, and pull-request resources—not by a separate Actions workflow.

Follow-up

Reimplement the feature as provider-managed unprotected branches plus normal downstream PRs. No direct default-branch writes or automatic merges.

[github-actions]

OpenTofu CI passed

View the workflow run.

Validation output (redacted, last 12000 characters)

Terraform validate.......................................................Passed
Terraform validate with tflint...........................................Passed
Checkov..................................................................Passed
Terraform fmt............................................................Passed
Terraform docs...........................................................Passed
Detect hardcoded secrets.................................................Passed
check for case conflicts.................................................Passed
check for merge conflicts................................................Passed
check for broken symlinks............................(no files to check)Skipped
check vcs permalinks.....................................................Passed
detect destroyed symlinks................................................Passed
detect private key.......................................................Passed
fix end of files.........................................................Passed
mixed line ending........................................................Passed
trim trailing whitespace.................................................Passed
don't commit to branch..................................................Skipped
check for added large files..............................................Passed

[github-actions]

OpenTofu Plan