csharp: Add EFL_BETA guards around new test

Summary:
The test method is not generated when beta is disabled as
`Eina.Value_Type` is marked @beta and eolian complains if we try to use
it.

Other `Eina.Value` methods work despite `Eina.Value` also being beta due
to its usage as stable through the keyword `any_value[_ptr]`.

Reviewers: vitor.sousa, bu5hm4n, felipealmeida

Reviewed By: vitor.sousa

Subscribers: cedric, #reviewers, #committers

Tags: #efl

Differential Revision: https://phab.enlightenment.org/D9449

src/tests/efl_mono/ValueEolian.cs

@@ -161,6 +161,9 @@ public static class TestEinaValueEolian {
         Test.AssertEquals(Eina.ValueType.Int32, received.GetValueType());
     }
 
+// ValueType in eolian context is beta, so not allowed.
+// Value does not have this problem as it is used as any_value/any_value_ptr
+#if EFL_BETA
     public static void TestEolianEinaValueTypeMarshalling()
     {
         var obj = new Dummy.TestObject();
@@ -171,6 +174,7 @@ public static class TestEinaValueEolian {
             Test.AssertEquals(type, obj.MirrorValueType(type));
         }
     }
+#endif
 }
 #pragma warning restore 1591
 }