Use constant to represent max length in safeToString

Author: mtoffl01

internal-api/src/main/java/datadog/trace/bootstrap/config/provider/stableconfig/StableConfigMappingException.java

@@ -1,15 +1,17 @@
 package datadog.trace.bootstrap.config.provider.stableconfig;
 
 public class StableConfigMappingException extends RuntimeException {
+  private static final int maxLen = 10;
+
   public StableConfigMappingException(String message) {
     super(message);
   }
 
   public static String safeToString(Object value) {
     if (value == null) return "null";
     String str = value.toString();
-    if (str.length() > 100) {
-      return str.substring(0, 100) + "...(truncated)";
+    if (str.length() > maxLen) {
+      return str.substring(0, maxLen) + "...(truncated)";
     }
     return str;
   }