Fix realtime indicator animation not restarting on view recycling

[akimovpro]

Summary

Restart animation when view becomes visible again after being recycled by the list adapter. Clear old animations before starting new ones to prevent stacking.

Fixes #818

Changes

• Override onVisibilityChanged() in RealtimeIndicatorView to restart animation when view becomes VISIBLE and stop it when hidden
• Call clearAnimation() at the start of initAnimation() to prevent animation stacking on recycled views

Test plan

• Open a stop with many arrivals (transit center)
• Scroll down until initial arrivals go offscreen
• Scroll back up – indicators should still animate
• Indicator colors should match "min" text color

---

• Apply the AndroidStyle.xml style template to your code in Android Studio.
• Run the unit tests with gradlew connectedObaGoogleDebugAndroidTest to make sure you didn't break anything
• If you have multiple commits please combine them into one commit by squashing them for the initial submission of the pull request.

[CLAassistant]

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