UI: Revert design changes to data-block selector for the 2.92 release

Partially reverts 2250b5cefe.

Removing the user count and fake user count icons was controversial (which was
expected) and there are a few further changes needed, that won't make it in
time for the release, see D9946.
While there is a design to bring back the user count and fake user indicators,
a new design idea was proposed that the UI team wants to follow. This came too
late for the 2.92 release, the new design is targeted at the 2.93 release now.
Meanwhile, UI team decision was to simply revert the design changes.

The new design is being worked on in https://developer.blender.org/T84669.

Note that this commit does not revert some internal changes done in
2250b5cefe. Namely the introduction of `ed_util_ops.c` and data-block
operators in there. These will still be needed in the new design.

source/blender/editors/interface/interface_ops.c

@@ -1521,7 +1521,6 @@ static int edittranslation_exec(bContext *C, wmOperator *op)
 
     UI_but_string_info_get(C,
                            but,
-                           NULL,
                            &but_label,
                            &rna_label,
                            &enum_label,