Construct SSH welcome message in provision API

Build the welcome header, message of the day, and greeting in the
provision endpoint so the SSH proxy can display it on connection.
Also remove verbose per-request key count logging.

Author: Nils Bars

webapp/ref/view/api.py

@@ -15,6 +15,7 @@
     ExerciseImageManager,
     InconsistentStateError,
     InstanceManager,
+    admin_required,
     utc_datetime_to_local_tz,
     datetime_to_string,
 )
@@ -107,7 +108,16 @@ def start_and_return_instance(
     exercise: Exercise = instance.exercise
 
     # Message that is printed before the user is dropped into the container shell.
-    welcome_message = ""
+    # Include the SSH welcome header and greeting (previously displayed by ssh-wrapper).
+    header = SystemSettingsManager.SSH_WELCOME_MSG.value or ""
+    msg_of_the_day = SystemSettingsManager.SSH_MESSAGE_OF_THE_DAY.value
+    if msg_of_the_day:
+        header += f"\n{ansi.green(msg_of_the_day)}"
+
+    user_name = requesting_user.full_name
+    greeting = f"Hello {user_name}!\n[+] Connecting to task \"{exercise.short_name}\"..."
+
+    welcome_message = f"{header}\n{greeting}\n"
 
     if not instance.is_submission():
         latest_submission = instance.get_latest_submission()