executable-model test failure in test-compiler-integration PolymorphismTest

org.drools.mvel.integrationtests.PolymorphismTest in test-compiler-integration fails with some tests when executable-model is enabled. See TODO comment in the test class. Once fixed (or the test failure is justified), we can remove the TODO comment and let the test run with executable-model.

Currently, executable-model is disabled:

        // TODO: ....
        return TestParametersUtil.getKieBaseCloudConfigurations(false);

If the test failure contains multiple bugs, we may split this JIRA into multiple JIRAs.