Avoid resize (cpu/mem) actions for container reservation with a small amount of change

[maxwangvmt]

Some actions to resize down cpu/mem reservation for containers with a very small change have been observed. For example, I have observed many actions like resizing cpu reservation from 6MHz to 4.5MHz, which seems not helpful as the change 1.5MHz is very small.

Since the cost of resize actions can't be ignored, we need to avoid actions that buy little to us.

[maxwangvmt]

[enlinxu]

This is definitely an issue. But at the same time, the settings here may not be that realistic. We can consider fixing it later.