[kueuectl] Use the fake time instead of real in tests

[mbobrovskyi]

What would you like to be cleaned:
Introduce the same approach as controllers like this:

kueue/pkg/controller/core/workload_controller.go

Line 117 in 4b9744b

clock clock.Clock

kueue/pkg/controller/core/workload_controller_test.go

Line 807 in 4b9744b

reconciler.clock = testingclock.NewFakeClock(testStartTime)

Also check this.

Why is this needed:

[mszadkow]

/assign