[Misc] fix SplittableRandomTest.java intermittently timeout

Summary: fix jdk/test/java/util/SplittableRandom/SplittableRandomTest.java intermittently fail, use /dev/urandom instead of /dev/random to avoid block for SecureRandom API

Test Plan: CI pipeline

Reviewed-by: lvfei.lv, lei.yul

Issue: #428

Author: sendaoYan

jdk/test/java/util/SplittableRandom/SplittableRandomTest.java

@@ -36,8 +36,8 @@
 
 /**
  * @test
- * @run testng SplittableRandomTest
- * @run testng/othervm -Djava.util.secureRandomSeed=true SplittableRandomTest
+ * @run testng/othervm -Djava.security.egd=file:/dev/urandom SplittableRandomTest
+ * @run testng/othervm -Djava.security.egd=file:/dev/urandom -Djava.util.secureRandomSeed=true SplittableRandomTest
  * @summary test methods on SplittableRandom
  * @key randomness
  */