The parameters model contains multiple copies of FeatureFlags

`FeatureFlags`/`HyperionFeatureFlags` is exposed by `WithHyperionUDCFeatures`
`WithHyperionUDCFeatures` is inherited by many different parameter classes, some of which aggregate instances of each other, this leads to multiple copies of the `FeatureFlags` being present.

`FeatureFlags` is stateful; it requires `update_self_from_server()` to be invoked to fetch the current config server state and override the defaults.

Not doing this consistently/failing to replicate the state across instances can lead to bugs.

`FeatureFlags` shouldn't really be in the parameter model anyway as it's not determined on a per-request basis.
It should be injected separately as context at the entry of each plan, and to callbacks where it's needed for event handling.