fix: Update conversation read status indicator logic (#5777)

app/javascript/dashboard/store/modules/conversations/index.js

@@ -13,7 +13,6 @@ const state = {
   currentInbox: null,
   selectedChatId: null,
   appliedFilters: [],
-  conversationLastSeen: null,
 };
 
 // mutations
@@ -34,9 +33,6 @@ export const mutations = {
     _state.allConversations = [];
     _state.selectedChatId = null;
   },
-  [types.SET_CONVERSATION_LAST_SEEN](_state, timestamp) {
-    _state.conversationLastSeen = timestamp;
-  },
   [types.SET_ALL_MESSAGES_LOADED](_state) {
     const [chat] = getSelectedChatConversation(_state);
     Vue.set(chat, 'allMessagesLoaded', true);