Fire a pixel when removing the VPN configuration

[samsymons]

Task/Issue URL: https://app.asana.com/0/414235014887631/1207698850203829/f Tech Design URL: CC:

Description:

This PR adds a pixel that reports when the VPN configuration has been removed, and why.

Steps to test this PR:

1. Install the VPN and then sign out of Privacy Pro
2. Check that you see a pixel in the logs, and that the configuration was removed
3. Check the codebase to make sure we aren't calling removeFromPreferences() anywhere outside of the tunnel controller, to make sure there are no paths that aren't covered by the pixel
4. Check that the removal reasons make sense

Definition of Done (Internal Only):

• [ ] Does this PR satisfy our Definition of Done?

Copy Testing:

• [ ] Use of correct apostrophes in new copy, ie ’ rather than '

Orientation Testing:

• [ ] Portrait
• [ ] Landscape

Device Testing:

• [ ] iPhone SE (1st Gen)
• [ ] iPhone 8
• [ ] iPhone X
• [ ] iPhone 14 Pro
• [ ] iPad

OS Testing:

• [ ] iOS 14
• [ ] iOS 15
• [ ] iOS 16

Theme Testing:

• [ ] Light theme
• [ ] Dark theme

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Internal references:

Software Engineering Expectations Technical Design Template