Remove CODY_FOCUS_SIDEBAR_ON_STARTUP

[umpox]

Description

Removes the auto focusing of Cody when we start local development.

The reasoning is that this is not a typical flow for any of our users. We are possibly building false assumptions and even missing bugs by doing this.

Also:

• Some logic only runs when the sidebar is open, always having the sidebar open from the start means we can miss some bugs when this code doesn't run (Autocomplete: Fix codebase context inference for embeddings #525)
• The sidebar is no longer the obvious way to interact with Cody. We're possibly overemphasising parts of this because it's always visible to us.

Test plan

Local dev change, tested by running local dev

[taras-yemets]

It makes sense to me! Thank you, Tom!