In RTL editor indent performs outdent and vise versa

[mark-k]

1. In hebrew localization start editing a post
2. start a unordered list
3. add an item to the list
4. try to outdent it (the first button of the indent/outdent pair from the right as expected)
5. the item was indented

the action performed is not consistent with the icon, but it is consistent with the tooltip text.

[SergeyBiryukov]

Duplicate of #21281.