Summary:
Fix a bug where `CACurrentMediaTime` was being used to calculate the elapsed frame time, even though it's not comparable to `NSDate.timeIntervalSince1970` time.
## Changelog
[iOS] [Fixed] - callIdleCallbacks deadline calculation
Pull Request resolved: https://github.com/facebook/react-native/pull/26114
Test Plan: None
Differential Revision: D17314125
Pulled By: cpojer
fbshipit-source-id: 5061a3954371df2134f0c77dc260228668abe747