Change behavior when exception occurred in InitExecutor. Will not call System.exit(), just print stack trace

sentinel-core/src/main/java/com/alibaba/csp/sentinel/init/InitExecutor.java

@@ -56,7 +56,6 @@ public final class InitExecutor {
         } catch (Exception ex) {
             RecordLog.info("[Sentinel InitExecutor] Init failed", ex);
             ex.printStackTrace();
-            System.exit(-1);
         }
     }