docs: Remove reference to non-existing binding for `tab switcher: toggle all` (#45919)

Haojian Wu created 

There is no default binding for `{#kb tab_switcher::ToggleAll}`, so the
doc is rendered as:

<img width="1330" height="227" alt="image"
src="https://github.com/user-attachments/assets/a5ce2efd-69c4-4eb4-a28b-3fdb7825ce34"
/>

Release Notes:

- N/A

Change summary

docs/src/tab-switcher.md | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)

Detailed changes

docs/src/tab-switcher.md 🔗 

@@ -20,10 +20,8 @@ the switcher is closed.
 
 ## Opening the Tab Switcher
 
-The Tab Switcher can also be opened with either {#action tab_switcher::Toggle}
-or {#action tab_switcher::ToggleAll}. Using {#kb tab_switcher::Toggle} will show
-only the tabs for the current pane, while {#kb tab_switcher::ToggleAll} shows
-all tabs for all panes.
+The Tab Switcher can also be opened with either {#action tab_switcher::Toggle} ({#kb tab_switcher::Toggle})
+or {#action tab_switcher::ToggleAll}.
 
 While the Tab Switcher is open, you can: