AttributeError: 'delete_after'
Sentry Issue: [BOT-147](https://sentry.io/organizations/python-discord/issues/2466022929/?referrer=github_integration)

```
Forbidden: 403 Forbidden (error code: 50007): Cannot send messages to this user
  File "bot/exts/help_channels/_cog.py", line 586, in notify_session_participants
    await message.author.send(embed=embed)
  File "discord/abc.py", line 935, in send
    data = await state.http.send_message(channel.id, content, tts=tts, embed=embed,
  File "discord/http.py", line 241, in request
    raise Forbidden(r, data)

KeyError: 'delete_after'
  File "bot/constants.py", line 183, in __getattr__
    return _CONFIG_YAML[cls.section][name]

AttributeError: 'delete_after'
(1 additional frame(s) were not displayed)
...
  File "bot/exts/help_channels/_cog.py", line 473, in on_message
    await self.notify_session_participants(message)
  File "bot/utils/lock.py", line 108, in wrapper
    except discord.Forbidden:
  File "bot/utils/lock.py", line 108, in wrapper
    except discord.Forbidden:
  File "bot/exts/help_channels/_cog.py", line 597, in notify_session_participants
    delete_after=RedirectOutput.delete_after
  File "bot/constants.py", line 191, in __getattr__
    raise AttributeError(repr(name)) from e

Unhandled exception in on_message.
```
diff --git a/bot/exts/help_channels/_cog.py b/bot/exts/help_channels/_cog.py
index a9b84758..35658d11 100644
--- a/bot/exts/help_channels/_cog.py
+++ b/bot/exts/help_channels/_cog.py
@@ -594,7 +594,7 @@ class HelpChannels(commands.Cog):
                 await bot_commands_channel.send(
                     f"{message.author.mention} {constants.Emojis.cross_mark} "
                     "To receive updates on help channels you're active in, enable your DMs.",
-                    delete_after=RedirectOutput.delete_after
+                    delete_after=RedirectOutput.delete_delay
                 )
                 return
 
['bot/exts/help_channels/_cog.py']