[serve] Fix small bugs (ray-project#39778)

Fix two bugs:
1. Application target state checkpoint is not deleted when Serve is shutdown, so you will see `Recovering target state for application 'default' from checkpoint` each time you start Serve again. It "recovers" the default target state so there is no actual difference, but this is still a bug and the confusing log is printed to console + log files.
<img width="1202" alt="Screen Shot 2023-09-20 at 3 35 19 PM" src="https://github.com/ray-project/ray/assets/15851518/85a63678-6c99-4e3c-a2fd-9b795b0e10dd">

2. Typo in `deploy_config`. We have a generic catch block in case unexpected errors are thrown, had a typo in that block (which is untested since it's for unexpected errors).

python/ray/serve/_private/application_state.py

@@ -352,7 +352,7 @@ def deploy_config(
             except Exception:
                 self._set_target_state_deployment_infos(None)
                 self._update_status(
-                    BuildAppStatus.FAILED,
+                    ApplicationStatus.DEPLOY_FAILED,
                     (
                         f"Unexpected error occured while applying config for "
                         f"application '{self._name}': \n{traceback.format_exc()}"
@@ -846,6 +846,8 @@ def shutdown(self) -> None:
         for app_state in self._application_states.values():
             app_state.delete()
 
+        self._kv_store.delete(CHECKPOINT_KEY)
+
     def is_ready_for_shutdown(self) -> bool:
         """Return whether all applications have shut down.
 

python/ray/serve/tests/test_standalone_2.py

@@ -379,5 +379,38 @@ def __call__(self):
         )
 
 
+def test_checkpoint_deleted_on_serve_shutdown(start_and_shutdown_ray_cli_function):
+    """Test the application target state checkpoint is deleted when Serve is shutdown"""
+
+    file1 = """from ray import serve
+@serve.deployment
+class A:
+    def __call__(self):
+        return "Hello A"
+serve.run(A.bind())"""
+
+    file2 = """from ray import serve
+@serve.deployment
+class B:
+    def __call__(self):
+        return "Hello B"
+serve.run(B.bind())"""
+
+    with NamedTemporaryFile() as f1, NamedTemporaryFile() as f2:
+        f1.write(file1.encode("utf-8"))
+        f1.seek(0)
+        output = subprocess.check_output(["python", f1.name], stderr=subprocess.STDOUT)
+        print(output.decode("utf-8"))
+        assert "Connecting to existing Ray cluster" in output.decode("utf-8")
+        subprocess.check_output(["serve", "shutdown", "-y"])
+
+        f2.write(file2.encode("utf-8"))
+        f2.seek(0)
+        output = subprocess.check_output(["python", f2.name], stderr=subprocess.STDOUT)
+        print(output.decode("utf-8"))
+        assert "Connecting to existing Ray cluster" in output.decode("utf-8")
+        assert "Recovering target state for application" not in output.decode("utf-8")
+
+
 if __name__ == "__main__":
     sys.exit(pytest.main(["-v", "-s", __file__]))