Use `shallNotBeReferencedFields` for ScheduledSession.SessionSeries feeds

[civsiv]

It is incorrect for ScheduledSession.SessionSeries fields to have compact ID references, unlike SessionSeries feeds.

// Valid
{
    "kind": "ScheduledSession.SessionSeries",
    "data": {
        "@type": "ScheduledSession",
        "superEvent": {
            "@type": "SessionSeries",
            "@id": "https://example.com/SessionSeries/1"
            ...
        }
        ...
    },
    ...
}

// Invalid
{
    "kind": "ScheduledSession.SessionSeries",
    "data": {
        "@type": "ScheduledSession",
        "superEvent": "https://example.com/SessionSeries/1"
        ...
    },
    ...
}