saved searches: always show 'Saved searches' link in navbar.

* Always display 'Saved searches' link in subnav bar, even if the user
  hasn't created any saved searches yet.
* Eliminate use of `has_saved_searches` bitpref on users.

app/models/saved_search.rb

@@ -151,8 +151,6 @@ class SavedSearch < ApplicationRecord
   belongs_to :user
   validates :query, presence: true
   validate :validate_count
-  before_create :update_user_on_create
-  after_destroy :update_user_on_destroy
   before_validation :normalize_query
   before_validation :normalize_labels
   scope :labeled, ->(label) { label.present? ? where("labels @> string_to_array(?, '~~~~')", label) : where("true") }
@@ -163,18 +161,6 @@ class SavedSearch < ApplicationRecord
     end
   end
 
-  def update_user_on_create
-    if !user.has_saved_searches?
-      user.update(has_saved_searches: true)
-    end
-  end
-
-  def update_user_on_destroy
-    if user.saved_searches.count == 0
-      user.update(has_saved_searches: false)
-    end
-  end
-
   def disable_labels=(value)
     CurrentUser.update(disable_categorized_saved_searches: true) if value.to_s.truthy?
   end

app/models/user.rb

@@ -32,6 +32,7 @@ class User < ApplicationRecord
   # - disable_tagged_filenames (enabled by 387)
   # - enable_recent_searches (enabled by 499)
   # - disable_cropped_thumbnails (enabled by 22)
+  # - has_saved_searches
   BOOLEAN_ATTRIBUTES = %w(
     is_banned
     has_mail

app/views/posts/partials/common/_secondary_links.html.erb

@@ -8,9 +8,7 @@
   <% unless CurrentUser.is_anonymous? %>
     <%= subnav_link_to "Favorites", posts_path(tags: "ordfav:#{CurrentUser.user.name}") %>
     <%= subnav_link_to "Fav groups", favorite_groups_path %>
-    <% if CurrentUser.has_saved_searches? %>
-      <%= subnav_link_to "Saved searches", posts_path(:tags => "search:all") %>
-    <% end %>
+    <%= subnav_link_to "Saved searches", posts_path(tags: "search:all") %>
   <% end %>
   <%= subnav_link_to "Changes", post_versions_path %>
   <% if CurrentUser.can_approve_posts? %>

app/views/users/_statistics.html.erb

@@ -170,7 +170,7 @@
       <% end %>
 
       <% if CurrentUser.id == user.id %>
-        <% if CurrentUser.has_saved_searches? %>
+        <% if SavedSearch.labels_for(CurrentUser.user.id).present? %>
           <tr>
             <th>Saved Searches</th>
             <td>