clean up fetch_bottle_tab

Library/Homebrew/formula_installer.rb

@@ -1282,16 +1282,18 @@ on_request: installed_on_request?, options:)
 
   sig { void }
   def fetch_bottle_tab
-    @fetch_bottle_tab ||= begin
+    return if @fetch_bottle_tab
+
+    begin
       formula.fetch_bottle_tab
       @bottle_tab_runtime_dependencies = formula.bottle_tab_attributes
                                                 .fetch("runtime_dependencies", []).then { |deps| deps || [] }
                                                 .each_with_object({}) { |dep, h| h[dep["full_name"]] = dep }
                                                 .freeze
-      true
     rescue DownloadError, ArgumentError
-      @fetch_bottle_tab = T.let(true, T.nilable(TrueClass))
+      # do nothing
     end
+    @fetch_bottle_tab = T.let(true, T.nilable(TrueClass))
   end
 
   sig { void }