Remove FXIOS-11248 Remove usage of UIColor.Photon.Grey60

[bmihai23]

📜 Tickets

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💡 Description

• Removed photon color Grey60

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• Filled in the above information (tickets numbers and description of your work)
• Updated the PR name to follow our PR naming guidelines
• Wrote unit tests and/or ensured the tests suite is passing
• When working on UI, I checked and implemented accessibility (minimum Dynamic Text and VoiceOver)
• If needed, I updated documentation / comments for complex code and public methods
• If needed, added a backport comment (example @Mergifyio backport release/v120)

[lmarceau]

Hello! The class func replace(_ base: String, keys: [String], replacements: [String]) -> NSMutableAttributedString isn't called anymore. We can remove it from the code I think