Fix focusing terminal when running tasks (#13675)

After removing the unnecessary reveal strategy handling:



[focus-task-fix.webm](https://github.com/zed-industries/zed/assets/39293/93afd332-8f22-47f5-914d-5bc040e24029)

When running tasks, the terminal was not focused when the terminal had
to be replaced. This is because the code for revealing the terminal had
been executed twise: once inside `replace_terminal` function and also at
the end of `spawn_task`.

Fixes #13674

Release Notes:

- Fixed focusing the terminal when re-spawning a task
([#13674](https://github.com/zed-industries/zed/issues/13674))