Fix WindowMagnificationAnimationControllerTest fail

The root cause is that we are using different types (int and float) between the code base and the test case. If we convert a floating-point number to an integer, the decimal part of the float value is truncated. But, the round() method rounds upward if the value after the decimal is greater than or equal to 5.

Bug: 290648269
Test: atest WindowMagnificationAnimationControllerTest (Pixel 7 & Pixel Fold)
Change-Id: I0ae0f69e9078f998f5d6c08b2aefbe00e1628af9