Remove default keybinds for navigating between docks/editors (#7381)

Turns out that these keybindings are active in Vim *and* in non-Vim mode
and they shadow `Ctrl-w` in terminals.

We should fix `Ctrl-w` being shadowed, but until then let's remove the
default keybindings.

Release Notes:

- N/A

Co-authored-by: Kirill <kirill@zed.dev>
Co-authored-by: Conrad <Conrad@zed.dev>