refactor: IntroductionActivity (ViewBinding)

[david-allison]

• Part of Add View Binding #11116

Approach

• Cherry picked david-allison@386dbf2
• removed binding reference as unnecessary
• fixed outdated docs

How Has This Been Tested?

Brief test:

• Pixel 9 Pro API 36 Emulator - screen opens

Checklist

• You have a descriptive commit message with a short title (first line, max 50 chars).
• You have commented your code, particularly in hard-to-understand areas
• You have performed a self-review of your own code
• UI changes: include screenshots of all affected screens (in particular showing any new or changed strings)
• UI Changes: You have tested your change using the Google Accessibility Scanner

[lukstbit]

Starting still works, let's get this in...