Improve clock carousel perf

1. Only call clockViewFactory.getRatio() when set up the carousel,
   instead of whenever scrolling the carousel or populating the views
2. Remove unnessary onClockTransitionCompleted call
3. Do not call jumpToIndex if the current index is the same to avoid
   populating the views again

Test: Manually tested that the carousel works as expected.
Bug: 278850684
Change-Id: I9dc22f6df9052677db7330e7b5dd44b27722118f