Fixed outline panel space key behavior by removing duplicate toggle call

The `open_selected_entry` function in `outline_panel.rs` was incorrectly
calling `self.toggle_expanded(&selected_entry, window, cx)` in addition
to its primary logic, causing the space key to both open/close entries
AND toggle their expanded state. Removed the redundant `toggle_expanded`
call to achieve the intended behavior.

Closes #41711

Release Notes:

- Fixed issue with the outline panel where pressing space would cause an
open selected entry to collapse and cause a closed selected entry to
open.

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Co-authored-by: Smit Barmase <heysmitbarmase@gmail.com>