The current default loop iteration for VectorAPI jtreg tests is 100 (see: https://github.com/openjdk/jdk/blob/master/test/jdk/jdk/incubator/vector/config.sh#L41). It is too small to make the tested method hot enough to be compiled with C2.

Currently we met an issue that the back-end match rules missing cannot report the "bad AD file" crash when running VectorAPI tests with Arm NEON/SVE. However, if using a larger loop iteration (1000) for the tests, the crash can be reported by C2. So to guarantee the tests effectiveness, it's better to set a larger default iteration.