Revert "refactor(agent-images): use explicit Debian base"

This reverts commit 51b82f80d1.

tests/unit/test_builtin_agent_images.py

@@ -18,18 +18,7 @@ class TestBuiltinAgentImages(unittest.TestCase):
             with self.subTest(provider=dockerfile.parent.name):
                 self.assertRegex(
                     dockerfile.read_text(),
-                    r"(?m)^FROM debian:trixie-slim\s*$",
-                )
-
-    def test_all_create_node_runtime_user(self):
-        for dockerfile in _AGENT_DOCKERFILES:
-            with self.subTest(provider=dockerfile.parent.name):
-                dockerfile_text = dockerfile.read_text()
-                self.assertIn("groupadd --gid 1000 node", dockerfile_text)
-                self.assertIn(
-                    "useradd --uid 1000 --gid node --shell /bin/bash "
-                    "--create-home node",
-                    dockerfile_text,
+                    r"(?m)^FROM node:22-trixie-slim\s*$",
                 )
 
     def test_all_install_podman(self):