Reduce 2030-long-running-child heap requirements This avoids gcstress failures. We apparently run gcstress with a 16MB heap. This used to generate around 20MB of live data, now reduced to 10MB. Bug: 147619421 Test: art/test/run-test --host --gcstress 2030-long-running-child Change-Id: If05fdfbbdcd389e2c345f84219349a0e99c621e5