subscription_info: Add option to get partial subscribers.

It returns just bots for now.

zerver/lib/home.py

@@ -1,4 +1,5 @@
 import calendar
+import os
 import time
 from dataclasses import dataclass
 
@@ -108,6 +109,7 @@ def build_page_params_for_home_page_load(
     if user_profile is not None:
         client = RequestNotes.get_notes(request).client
         assert client is not None
+        partial_subscribers = os.environ.get("PARTIAL_SUBSCRIBERS") is not None
         state_data = do_events_register(
             user_profile,
             realm,
@@ -120,6 +122,7 @@ def build_page_params_for_home_page_load(
             client_capabilities=client_capabilities,
             narrow=narrow,
             include_streams=False,
+            include_subscribers="partial" if partial_subscribers else True,
         )
         queue_id = state_data["queue_id"]
         default_language = state_data["user_settings"]["default_language"]