Remove request reading middleware as we use post-buffering (#2094)

# What this PR does

RequestBodyReadingMiddleware is excess as [post-buffering is
enabled](https://github.com/grafana/oncall/blob/dev/engine/uwsgi.ini#L17):

If an HTTP request has a body (like a POST request generated by a form),
you have to read (consume) it in your application. If you do not do
this, the communication socket with your webserver may be clobbered. If
you are lazy you can use the post-buffering option that will
automatically read data for you. For Rack applications this is
automatically enabled.
(https://uwsgi-docs.readthedocs.io/en/latest/ThingsToKnow.html)

## Which issue(s) this PR fixes

## Checklist

- [ ] Unit, integration, and e2e (if applicable) tests updated
- [ ] Documentation added (or `pr:no public docs` PR label added if not
required)
- [ ] `CHANGELOG.md` updated (or `pr:no changelog` PR label added if not
required)

engine/engine/middlewares.py

@@ -3,9 +3,8 @@ import logging
 
 from django.apps import apps
 from django.conf import settings
-from django.core.exceptions import PermissionDenied, RequestDataTooBig
+from django.core.exceptions import PermissionDenied
 from django.db import OperationalError
-from django.http import HttpResponse
 from django.utils.deprecation import MiddlewareMixin
 
 logger = logging.getLogger(__name__)
@@ -57,19 +56,6 @@ class RequestTimeLoggingMiddleware(MiddlewareMixin):
         return response
 
 
-class RequestBodyReadingMiddleware(MiddlewareMixin):
-    def process_request(self, request):
-        # Reading request body, as required by uwsgi
-        # https://uwsgi-docs.readthedocs.io/en/latest/ThingsToKnow.html
-        # "If an HTTP request has a body (like a POST request generated by a form),
-        # you have to read (consume) it in your application.
-        # If you do not do this, the communication socket with your webserver may be clobbered."
-        try:
-            request.body
-        except RequestDataTooBig:
-            return HttpResponse(status=400)
-
-
 class BanAlertConsumptionBasedOnSettingsMiddleware(MiddlewareMixin):
     """
     Banning requests for /integrations/v1

engine/settings/base.py

@@ -245,7 +245,6 @@ MIDDLEWARE = [
     "log_request_id.middleware.RequestIDMiddleware",
     "engine.middlewares.RequestTimeLoggingMiddleware",
     "engine.middlewares.BanAlertConsumptionBasedOnSettingsMiddleware",
-    "engine.middlewares.RequestBodyReadingMiddleware",
     "django.middleware.security.SecurityMiddleware",
     "whitenoise.middleware.WhiteNoiseMiddleware",
     "debug_toolbar.middleware.DebugToolbarMiddleware",