test: rename realistic-CI test, fix env_var note

The previous name oversold the scenario - credentials aren't "absent",
they're stringified placeholders. Jinja `env_var('FOO')` with FOO
unset renders the literal string "None" into the YAML, which Pydantic
accepts for Postgres's `user`/`password` (both typed `str`). The test
proves the gate prevents a connection attempt, not that credentials
are missing. Renamed to test_format_does_not_open_state_connection
and rewrote the docstring to describe what actually happens.

Coding-Agent: pi
Model: anthropic/claude-opus-4-7
Signed-off-by: Joe Hartshorn <8881940+j-hartshorn@users.noreply.github.com>

Author: j-hartshorn

tests/cli/test_cli.py

@@ -2304,16 +2304,20 @@ def test_plan_still_loads_state(runner: CliRunner, tmp_path: Path, mocker):
     assert mock.called, "state-sync was never accessed during `plan`"
 
 
-def test_format_runs_without_state_credentials(
+def test_format_does_not_open_state_connection(
     runner: CliRunner, tmp_path: Path, mocker, monkeypatch
 ):
     """Realistic CI scenario: a config.yaml declaring a remote Postgres state
     connection with credentials sourced from unset env vars. Format must still
     succeed without opening the state connection.
 
     Distinct from test_format_runs_without_state: that one proves the gate by
-    patching get_versions. This one proves the end-to-end CI use case where
-    no secrets are provisioned and YAML env_var() resolves to None.
+    patching get_versions on a default-DuckDB project. This one proves the
+    end-to-end CI use case where the config declares a real remote backend and
+    no secrets are provisioned. Jinja `env_var('FOO')` with `FOO` unset
+    renders the string `"None"` into the YAML; Pydantic accepts that for
+    Postgres's `user`/`password` (both typed `str`), so config validation
+    passes with placeholder values. The gate then prevents any connection.
     """
     pytest.importorskip("psycopg2")