Cleanup: use FILE_MAX instead of PATH_MAX for sequencer add code

This is clamped by StripElem::name which is a filename component,
so no need to use PATH_MAX which is much larger.

source/blender/editors/space_sequencer/sequencer_add.c

@@ -1246,8 +1246,8 @@ void sequencer_image_seq_reserve_frames(
   RNA_END;
 
   if (filename) {
-    char ext[PATH_MAX];
-    char filename_stripped[PATH_MAX];
+    char ext[FILE_MAX];
+    char filename_stripped[FILE_MAX];
     /* Strip the frame from filename and substitute with `#`. */
     BLI_path_frame_strip(filename, ext, sizeof(ext));