Revert "add config `update.unbuffered`"

This reverts commit b1350a668c.

Parallel updates are a great feature, but they break color.ui and
attempts to fix that have caused unexpected exceptions to be thrown on
Windows, so we need to back the feature out for now until we can get
it done in a way that works with both color and Windows.

Signed-off-by: Martí Bolívar <marti.bolivar@nordicsemi.no>

src/west/app/project.py

@@ -832,9 +832,6 @@ class Update(_ProjectCommand):
                                                         fallback=None)
         self.sync_submodules = config.getboolean('update', 'sync-submodules',
                                                  fallback=True)
-        self.unbuffered = args.unbuffered or config.getboolean('update',
-                                                               'unbuffered',
-                                                               fallback=False)
 
         self.group_filter: List[str] = []
 
@@ -894,7 +891,7 @@ class Update(_ProjectCommand):
         # XXX: this is not picklable
         self.parser = None
 
-        if self.unbuffered:
+        if self.args.unbuffered:
             logdir = None
             logdir_name = None
         else: