Fix flaky VibratorCallbackSchedulerTest

The test is sometimes timing out while asserting the scheduled callbacks
are triggered within the required test timeout.

Update CallbackScheduler to use std::condition_variable_any::wait_for
with calculated durations from using std::chrono::steady_clock, instead
of relying on the timestamps via wait_until.

Update the VibratorCallbackSchedulerTest to also use wait_for.

Bug: 293603710
Test: VibratorCallbackSchedulerTest
Change-Id: Ie84147a9ff686d666d8525a35914571f32d72719