[fix/chores] Limit command results in device admin to 30

Author: nemesifier

openwisp_controller/connection/admin.py

@@ -105,7 +105,7 @@ class CommandInline(admin.StackedInline):
 
     def get_queryset(self, request, select_related=True):
         """
-        Return recent commands for this device
+        Return 30 most recent commands for this device
         (created within the last 7 days)
         """
         qs = super().get_queryset(request)
@@ -117,7 +117,7 @@ def get_queryset(self, request, select_related=True):
             ).order_by('-created')
         if select_related:
             qs = qs.select_related()
-        return qs
+        return qs[:30]
 
     def input_data(self, obj):
         return obj.input_data