Fix SIGHUP handler (#8697)

Fixes:

```
builtins.TypeError: _reload_logging_config() takes 1 positional argument but 2 were given
```

Author: richvdh

changelog.d/8697.misc

@@ -0,0 +1 @@
+ Re-organize the structured logging code to separate the TCP transport handling from the JSON formatting.

synapse/app/_base.py

@@ -49,7 +49,6 @@ def register_sighup(func, *args, **kwargs):
 
     Args:
         func (function): Function to be called when sent a SIGHUP signal.
-            Will be called with a single default argument, the homeserver.
         *args, **kwargs: args and kwargs to be passed to the target function.
     """
     _sighup_callbacks.append((func, args, kwargs))
@@ -251,13 +250,13 @@ def handle_sighup(*args, **kwargs):
                 sdnotify(b"RELOADING=1")
 
                 for i, args, kwargs in _sighup_callbacks:
-                    i(hs, *args, **kwargs)
+                    i(*args, **kwargs)
 
                 sdnotify(b"READY=1")
 
             signal.signal(signal.SIGHUP, handle_sighup)
 
-            register_sighup(refresh_certificate)
+            register_sighup(refresh_certificate, hs)
 
         # Load the certificate from disk.
         refresh_certificate(hs)