Revert "fix: support headless Gitea credentials"

This reverts commit efd1cf4ef6.

scripts/ralph_gitea_sync.py

@@ -31,13 +31,6 @@ STATUS_LABELS = {
 
 
 def credential_for(host: str) -> tuple[str, str]:
-    # Prefer explicitly injected process credentials for headless workers. They
-    # are never written to the repo or emitted in logs.
-    username = os.environ.get("GITEA_USERNAME")
-    password = os.environ.get("GITEA_TOKEN") or os.environ.get("GITEA_PASSWORD")
-    if password:
-        return username or "", password
-
     result = subprocess.run(
         ["git", "credential", "fill"],
         input=f"protocol=https\nhost={host}\n\n",