Settings code cleanup after the experiment

[tomasstrba]

Task/Issue URL:
https://app.asana.com/0/1148564399326804/1207440329716828/f
https://app.asana.com/0/1148564399326804/1207509504833411/f
https://app.asana.com/0/1148564399326804/1206864291180522/f
https://app.asana.com/0/1148564399326804/1206886662182519/f

Description:
This PR contains a code cleanup after the Settings experiment. It includes:

• Removal of old Settings code
• Removal of temporary pixels
• Removal of Voice Search settings from the Private Search category

Steps to test this PR:

1. Make sure all new pixels listed in Asana are removed
2. Make sure Voice Search setting is not present in the Private Search category
3. Test new Settings screen and make sure all settings work as expected

OS Testing:

• iOS 16

---

Internal references:

Software Engineering Expectations
Technical Design Template

[github-actions]

	Fails
🚫	Please, don't forget to add a link to the internal task

	Warnings
⚠️	PR has more than 500 lines of code changing. Consider splitting into smaller PRs if possible.

Generated by 🚫 dangerJS against 2e1ef0c

[dus7]

One thing to double check. Verified all settings are reachable and work as intended.