[iOS] Prevent contributors counting animation from firing on scroll

[woxtu]

Issue

• close Maybe ContributorsCount animation should only be at the beginning of screen transition #1001

Overview (Required)

• This PR prevents the contributors counting animation from firing on scroll

Links

Screenshot (Optional if screenshot test is present or unrelated to UI)

Before	After

Movie (Optional)

Before	After
Simulator.Screen.Recording.-.iPhone.15.Pro.-.2024-09-10.at.23.44.30.mp4	Simulator.Screen.Recording.-.iPhone.15.Pro.-.2024-09-10.at.23.51.47.mp4

[shin-usu]

[nits]
It seems like that we could make a single if statement by doing the following

    func animate() {
        let interval = duration / Double(totalContributor)
        Timer.scheduledTimer(withTimeInterval: interval, repeats: true) { time in
            if tracker >= totalContributor {
                time.invalidate()
                return
            }
            tracker += 1
        }
    }

[shin-usu]

I left comment, but current code is fine👍