test: fix path issue in functional test

- Correct the JERSEY3_TEMPLATE_DIR path
- All 4 functional tests now pass

Author: Chhida

modules/openapi-generator/src/test/java/org/openapitools/codegen/java/jersey3/JavaJersey3ErrorEntityFunctionalTest.java

@@ -41,7 +41,7 @@
 public class JavaJersey3ErrorEntityFunctionalTest {
 
     private static final String JERSEY3_TEMPLATE_DIR = 
-        "modules/openapi-generator/src/main/resources/Java/libraries/jersey3/";
+        "src/main/resources/Java/libraries/jersey3/";
 
     /**
      * Verify generated code includes errorEntity field in ApiException