Fix Support conditional exclude for classes

[arneee]

In #1099 support for ExcludeIf on class level was added, unfortunately the condition was inverted.

Current behavior would actually exclude this class:

/**
 * @Serializer\Exclude(if="false")
 */
class PersonAccount

However it should only exclude the class if the condition evaluates to true:

/**
 * @Serializer\Exclude(if="true")
 */
class PersonAccount

This was due to a copy mistake from Expose, which internal also uses Exclude, but with the condition negated and also due to a test scenario which was not very clear to udnerstand.

I have simplified the test to make it more clear and fixed the drivers.

[goetas]

Thanks!