Don't allow notdatadog in tests

pytest-socket resolves the hostnames in the --allow-hosts setting for
each test, so removing notdatadog saves ~4k DNS resolution attempts.

Note that the tests run with a stripe container present. Resolving the
stripe hostname doesn't result in a DNS resolution because getaddrinfo
resolves the name by reading the /etc/hosts file populated by Docker
(same story for localhost).

docker-compose.yml

@@ -138,8 +138,6 @@ services:
         condition: service_healthy
       stripe:
         condition: service_started
-      notdatadog:
-        condition: service_started
 
   files:
     image: warehouse:docker-compose

pyproject.toml

@@ -88,7 +88,7 @@ ignore_missing_imports = true
 [tool.pytest.ini_options]
 addopts = [
   "--disable-socket",
-  "--allow-hosts=localhost,::1,notdatadog,stripe",
+  "--allow-hosts=localhost,::1,stripe",
   "--durations=20",
   "--numprocesses=auto",
 ]