Fix CI: exclude Java 24+ codegen modules from Java 21 build, fix logging init

- Exclude json-java21-jtd-codegen and json-java21-jsonpath-codegen from
  the Java 21 CI build (they require JDK 24+ ClassFile API)
- Update test count to 653 (excluding codegen modules)
- Fix CodegenTestBase to handle empty logging level property in CI

To verify: mvn test -pl '!json-java21-jtd-codegen,!json-java21-jsonpath-codegen'

Author: simbo1905

.github/workflows/ci.yml

@@ -21,7 +21,7 @@ jobs:
           cache: 'maven'
 
       - name: Build and verify
-        run: mvn -B -DskipITs=false -DskipTests=false verify
+        run: mvn -B -DskipITs=false -DskipTests=false verify -pl '!json-java21-jtd-codegen,!json-java21-jsonpath-codegen'
 
       - name: Assert test count (no tests silently skipped)
         run: |
@@ -39,7 +39,7 @@ jobs:
                       for k in totals: totals[k]+=int(r.get(k,'0'))
                   except Exception:
                       pass
-          exp_tests=673
+          exp_tests=653
           exp_skipped=0
           if totals['tests']!=exp_tests or totals['skipped']!=exp_skipped:
               print(f"Unexpected test totals: {totals} != expected tests={exp_tests}, skipped={exp_skipped}")

json-java21-jsonpath-codegen/src/test/java/json/java21/jsonpath/codegen/CodegenTestBase.java

@@ -11,7 +11,10 @@ class CodegenTestBase {
 
     @BeforeAll
     static void configureLogging() {
-        final var levelName = System.getProperty("java.util.logging.ConsoleHandler.level", "INFO");
+        var levelName = System.getProperty("java.util.logging.ConsoleHandler.level", "INFO");
+        if (levelName == null || levelName.isBlank()) {
+            levelName = "INFO";
+        }
         final var level = Level.parse(levelName);
 
         final var rootLogger = Logger.getLogger("");