Enable the `graphql_release_data` feature flag by default

What does this MR do?

Makes the graphql_release_data feature flag enabled by default.

This allows users to start querying Release data through the GraphQL endpoint.

Previously, this data was hidden from the GraphQL schema using the feature_flag property. Now, the value of the release/releases field is simply toggled, which allows us to release the feature without losing the ability to turn it off if issues comes up.

When the graphql_release_data flag is disabled, the release/releases fields will still be visible in the GraphQL schema, but querying them will always result in null. (As described in our documentation.)

Related to #208702 (closed)