G1 remembered set memory footprint regression after JDK-8286115

JDK-8286115 changed ergonomic sizing of the "Array of Card Set" remembered set container to what the CSR/release note said.

This causes significantly increased memory usage in some benchmarks; it would have been better to change the specification according to the implementation.

In one extreme example, BigRAMTester, this causes a 30% peak-to-peak remembered set memory usage regression, see attached graph.

This graph shows jdk18 remembered set memory usage in green and jdk19 remembered set memory usage in yellow.

Total memory G1 GC usage rose from 1.2GB to 1.3GB (~+8.5%).

This issue can be mitigated by setting `G1RemSetArrayOfCardsEntries` to the previous value (twice the current value for a given region size).