helix: Unflip default split binds (#51962)

## Context

Closes #51955 

Some super easy helix parity. I checked and helix uses these binds for
splitting the editor, given these binds are helix specific, it would be
weird to just keep them being wrong.

## How to Review

just changed the default keymap for helix mode.

## Self-Review Checklist
- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
- [x] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

Release Notes:

- helix: fixed binds for splitting window

Co-authored-by: Bennet Bo Fenner <bennetbo@gmx.de>

assets/keymaps/vim.json

@@ -511,8 +511,8 @@
       "g shift-u": "git::UnstageAndNext", // Zed specific
 
       // Window mode
-      "space w v": "pane::SplitDown",
-      "space w s": "pane::SplitRight",
+      "space w v": "pane::SplitRight",
+      "space w s": "pane::SplitDown",
       "space w h": "workspace::ActivatePaneLeft",
       "space w j": "workspace::ActivatePaneDown",
       "space w k": "workspace::ActivatePaneUp",