MM-52532: Fix golangci warnings for public module (#23918)

https://mattermost.atlassian.net/browse/MM-52532

```release-note
NONE
```

server/public/model/websocket_message.go

@@ -177,16 +177,16 @@ type WebSocketEvent struct {
 // PrecomputeJSON precomputes and stores the serialized JSON for all fields other than Sequence.
 // This makes ToJSON much more efficient when sending the same event to multiple connections.
 func (ev *WebSocketEvent) PrecomputeJSON() *WebSocketEvent {
-	copy := ev.Copy()
-	event, _ := json.Marshal(copy.event)
-	data, _ := json.Marshal(copy.data)
-	broadcast, _ := json.Marshal(copy.broadcast)
-	copy.precomputedJSON = &precomputedWebSocketEventJSON{
+	evCopy := ev.Copy()
+	event, _ := json.Marshal(evCopy.event)
+	data, _ := json.Marshal(evCopy.data)
+	broadcast, _ := json.Marshal(evCopy.broadcast)
+	evCopy.precomputedJSON = &precomputedWebSocketEventJSON{
 		Event:     json.RawMessage(event),
 		Data:      json.RawMessage(data),
 		Broadcast: json.RawMessage(broadcast),
 	}
-	return copy
+	return evCopy
 }
 
 func (ev *WebSocketEvent) Add(key string, value any) {
@@ -207,14 +207,14 @@ func NewWebSocketEvent(event, teamId, channelId, userId string, omitUsers map[st
 }
 
 func (ev *WebSocketEvent) Copy() *WebSocketEvent {
-	copy := &WebSocketEvent{
+	evCopy := &WebSocketEvent{
 		event:           ev.event,
 		data:            ev.data,
 		broadcast:       ev.broadcast,
 		sequence:        ev.sequence,
 		precomputedJSON: ev.precomputedJSON,
 	}
-	return copy
+	return evCopy
 }
 
 func (ev *WebSocketEvent) DeepCopy() *WebSocketEvent {
@@ -226,14 +226,14 @@ func (ev *WebSocketEvent) DeepCopy() *WebSocketEvent {
 		}
 	}
 
-	copy := &WebSocketEvent{
+	evCopy := &WebSocketEvent{
 		event:           ev.event,
 		data:            dataCopy,
 		broadcast:       ev.broadcast.copy(),
 		sequence:        ev.sequence,
 		precomputedJSON: ev.precomputedJSON.copy(),
 	}
-	return copy
+	return evCopy
 }
 
 func (ev *WebSocketEvent) GetData() map[string]any {
@@ -249,27 +249,27 @@ func (ev *WebSocketEvent) GetSequence() int64 {
 }
 
 func (ev *WebSocketEvent) SetEvent(event string) *WebSocketEvent {
-	copy := ev.Copy()
-	copy.event = event
-	return copy
+	evCopy := ev.Copy()
+	evCopy.event = event
+	return evCopy
 }
 
 func (ev *WebSocketEvent) SetData(data map[string]any) *WebSocketEvent {
-	copy := ev.Copy()
-	copy.data = data
-	return copy
+	evCopy := ev.Copy()
+	evCopy.data = data
+	return evCopy
 }
 
 func (ev *WebSocketEvent) SetBroadcast(broadcast *WebsocketBroadcast) *WebSocketEvent {
-	copy := ev.Copy()
-	copy.broadcast = broadcast
-	return copy
+	evCopy := ev.Copy()
+	evCopy.broadcast = broadcast
+	return evCopy
 }
 
 func (ev *WebSocketEvent) SetSequence(seq int64) *WebSocketEvent {
-	copy := ev.Copy()
-	copy.sequence = seq
-	return copy
+	evCopy := ev.Copy()
+	evCopy.sequence = seq
+	return evCopy
 }
 
 func (ev *WebSocketEvent) IsValid() bool {