Allow heap region sizes larger than 32M with larger card table entry sizes

JDK-8272773 investigates the impact of configuring the card table sizes, essentially allowing larger card table entry sizes.

Since G1 ties remembered sets to card table entry size, enlarging these would allow larger heap region sizes.

Investigate the impact of larger regions on applications; most likely this would affect (large) applications with many remembered set entries the most, so using something like BigRAMTester for evaluation would be useful.

Maybe determine a heuristic that with larger heap sizes scales the card table entry size and the (maximum) heap region size.