Refactor useFreeConnectorProgram() so it does not fire in OSS

[joeykmh]

Right now useFreeConnectorProgram() is called in several places in OSS which results in a useQuery() that ultimately fails. Due to the implementation, this failed query produces the desired effect (FCP UI is not rendered in OSS). But ideally we should not be calling this query at all in unsupported environments.

Instead, we should create a new FeatureItem that represents the FCP. This feature is permanently disabled in OSS, so it's a better fit for the FeatureService than the ExperimentService anyway.

In addition, this will avoid conflicts with the ongoing config provider refactor: #21456

cc @ambirdsall