Document that not all feature flags need to be removed
Due to the way we ended up implementing the feature flag checks -- implicitly in the feature_available?
methods we already use -- it's no longer the case that every feature flag needs to be removed once the feature is shipped.
For example, the batch comments feature is always behind a License.feature_available?
check, because it's gated by the license. This method will always perform a feature flag check. There's nothing to be removed there.
As a side benefit, should we ever need to disable the feature later, that's still possible.
cc @mdelaossa