Revert "fish: Enable vi key bindings as default"

This reverts commit 5ad9f571d4.

vi bindings are not helpful on command line. The default Ctrl-X like
bindings are better.

fish/.config/fish/config.fish

@@ -2,8 +2,6 @@ set PATH {$HOME}/.nix-profile/bin {$HOME}/.cargo/bin $PATH
 set -gx TERM tmux-256color
 set -gx NIX_PATH {$HOME}/.nix-defexpr/channels
 
-fish_vi_key_bindings
-
 export EDITOR='nvim'
 export BROWSER='firefox'
 export MANPAGER='nvim +Man!'