Enable attribution flag

[samsymons]

Task/Issue URL: https://app.asana.com/0/414235014887631/1207179335148911/f Tech Design URL: CC:

Description:

This PR enables the attribution flag added in https://github.com/duckduckgo/iOS/pull/2702. This is to be merged only after the creation of the Monday May 6 internal release, as we want it to go into the May 13 internal release instead.

Steps to test this PR:

1. See https://github.com/duckduckgo/iOS/pull/2702

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