Improve GC estimation strategy based on both absolute size and relative percentage

A better way of deciding whether GC should run or not might be by looking at the numbers computed in SizeDeltaGcEstimation from both an absolute size and relative percentage point of view. For example it would make sense to run compaction only if at least one criterion is met: "run if there is > 50% increase or more than 10GB".

Since the absolute threshold is already implemented (see SegmentGCOptions.SIZE_DELTA_ESTIMATION_DEFAULT), it would be nice to add also something like SegmentGCOptions.SIZE_PERCENTAGE_ESTIMATION_DEFAULT and use it in making the decision.