fix(rivetkit-core): cap SerializeState shutdown timeout at 15s#4742

NathanFlurry wants to merge 1 commit intosleep-cleanup/01-core-remove-prevent-sleeprivet-dev/rivet:sleep-cleanup/01-core-remove-prevent-sleepfrom

sleep-cleanup/02-serialize-state-timeout-15srivet-dev/rivet:sleep-cleanup/02-serialize-state-timeout-15sCopy head branch name to clipboard