APIv4 - Add test to ensure superfluous option groups are not created

[colemanw]

Overview

Adds a test to APIV4 to ensure creating a custom field doesn't always create an option group.

[civibot]

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[demeritcowboy]

I think this addition is useful regardless of other discussions, but not merging yet.

Note this only tests fields with html_type Text, which isn't the type involved in the other discussions.