tests: Migrate mocked Request to HostMockRequest.

This migrates some mocked Request class and mocked request achieved
with namedtuple in test_decorators and test_mirror_users to use the
refactored HostMockRequest.

Since weakref cannot be used with namedtuple, this old way of mocking a
request object should be migrated to using HostRequestMock. Only after
this change we can extract client from the request object and store it
via ZulipRequestNotes.

zerver/lib/test_helpers.py

@@ -29,6 +29,7 @@ import ldap
 import orjson
 from boto3.resources.base import ServiceResource
 from django.conf import settings
+from django.contrib.auth.models import AnonymousUser
 from django.db.migrations.state import StateApps
 from django.http import HttpRequest, HttpResponse, HttpResponseRedirect
 from django.http.request import QueryDict
@@ -58,6 +59,7 @@ from zerver.models import (
 )
 from zerver.tornado.handlers import AsyncDjangoHandler, allocate_handler_id
 from zerver.worker import queue_processors
+from zilencer.models import RemoteZulipServer
 from zproject.backends import ExternalAuthDataDict, ExternalAuthResult
 
 if TYPE_CHECKING:
@@ -289,10 +291,11 @@ class HostRequestMock(HttpRequest):
     def __init__(
         self,
         post_data: Dict[str, Any] = {},
-        user_profile: Optional[UserProfile] = None,
+        user_profile: Optional[Union[UserProfile, AnonymousUser, RemoteZulipServer]] = None,
         host: str = settings.EXTERNAL_HOST,
         client_name: Optional[str] = None,
         meta_data: Optional[Dict[str, Any]] = None,
+        tornado_handler: Optional[AsyncDjangoHandler] = DummyHandler(),
     ) -> None:
         self.host = host
         self.GET = QueryDict(mutable=True)
@@ -323,7 +326,7 @@ class HostRequestMock(HttpRequest):
 
         request_notes_map[self] = ZulipRequestNotes(
             log_data={},
-            tornado_handler=DummyHandler(),
+            tornado_handler=tornado_handler,
         )
 
     @property