[spark] ignore PaimonLambdaFunctionfunction_test.java

[cxzl25]

Purpose

Linked issue: close #xxx

When running some UT, it may generate the PaimonLambdaFunctionfunction_test.java file, and mvn may fail due to the check of apache-rat-plugin

org.apache.paimon.spark.JavaLambdaStringToMethodConverter#compileAndLoadMethod

        File sourceFile = new File(getSourceFileName(functionName));
        try (FileWriter writer = new FileWriter(sourceFile)) {
            writer.write(javaCode);
        }

Tests

API and Format

Documentation