users: Send "update" events when deactivating or reactivating users.

We now send "realm_user/update" (and "realm_bot/update" for bots)
events with "is_active" field when deactivating and reactivating
users, including bots.

We would want to use "remove" event for a user losing access
to another user for #10970, so it is better to use "update"
event for deactivation as we only update "is_active" field
in the user objects and the clients still have the data for
deactivated users.

Previously, we used to send "add" event for reactivation along
with complete user objects, but clients should have the data
for deactivated users as well, so an "update" event is enough
like we do when deactivating users.

zerver/lib/events.py

@@ -865,13 +865,6 @@ def apply_event(
             if not person["is_bot"]:
                 person["profile_data"] = {}
             state["raw_users"][person_user_id] = person
-        elif event["op"] == "remove":
-            state["raw_users"][person_user_id]["is_active"] = False
-            if include_subscribers:
-                for sub in state["subscriptions"]:
-                    sub["subscribers"] = [
-                        user_id for user_id in sub["subscribers"] if user_id != person_user_id
-                    ]
         elif event["op"] == "update":
             is_me = person_user_id == user_profile.id
 
@@ -980,16 +973,17 @@ def apply_event(
 
                 if "new_email" in person:
                     p["email"] = person["new_email"]
+
+                if "is_active" in person and not person["is_active"] and include_subscribers:
+                    for sub in state["subscriptions"]:
+                        sub["subscribers"] = [
+                            user_id for user_id in sub["subscribers"] if user_id != person_user_id
+                        ]
         else:
             raise AssertionError("Unexpected event type {type}/{op}".format(**event))
     elif event["type"] == "realm_bot":
         if event["op"] == "add":
             state["realm_bots"].append(event["bot"])
-        elif event["op"] == "remove":
-            user_id = event["bot"]["user_id"]
-            for bot in state["realm_bots"]:
-                if bot["user_id"] == user_id:
-                    bot["is_active"] = False
         elif event["op"] == "delete":
             state["realm_bots"] = [
                 item for item in state["realm_bots"] if item["user_id"] != event["bot"]["user_id"]