Fix unexpected audio stream transcoding when uploaded video is eligible to passthrough (#26608)

Co-authored-by: Claire <claire.github-309c@sitedethib.com>

lib/paperclip/transcoder.rb

@@ -37,14 +37,16 @@ module Paperclip
         @output_options['f']       = 'image2'
         @output_options['vframes'] = 1
       when 'mp4'
+        unless eligible_to_passthrough?(metadata)
           @output_options['acodec'] = 'aac'
           @output_options['strict'] = 'experimental'
 
-        if high_vfr?(metadata) && !eligible_to_passthrough?(metadata)
+          if high_vfr?(metadata)
             @output_options['vsync'] = 'vfr'
             @output_options['r'] = @vfr_threshold
           end
         end
+      end
 
       command_arguments, interpolations = prepare_command(destination)