Switch to Coretto

[MilesBHuff]

Switch to Amazon Coretto from GraalVM (#211), for more-standard behavior that uses less CPU for compilation.

Only consider GraalVM CE if willing to A/B test it in SettleScape's specific environment, because whether Graal is actually a win vs C2 is likely quite contextual, and without benchmarks we're willy-nilly swapping out battle-tested norms for thoughts & prayers.