Change grayscale tiff export toast warning to dtprint

src/imageio/format/tiff.c

@@ -1,6 +1,6 @@
 /*
     This file is part of darktable,
-    Copyright (C) 2010-2023 darktable developers.
+    Copyright (C) 2010-2024 darktable developers.
 
     darktable is free software: you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -240,7 +240,7 @@ int write_image(dt_imageio_module_data_t *d_tmp, const char *filename, const voi
   }
 
   if(d->shortfile && layers == 3)
-    dt_control_log(_("not a B&W image, will not export as grayscale"));
+    dt_print(DT_DEBUG_IMAGEIO, "[tiff export] '%s' is not a B&W image, not exporting as grayscale\n", filename);
 
   TIFFSetField(tif, TIFFTAG_SAMPLESPERPIXEL, layers);
   TIFFSetField(tif, TIFFTAG_BITSPERSAMPLE, (uint16_t)d->bpp);