As part of SPM-4041 we need routers to access some "special" timeseries flag that today are only present in the local catalog.

In SPM-3830 we will mirror those flags in the cluster catalog so that routers will be able to read them.

In order to fix a cyclic dependency between SPM-4041 and SPM-3830 we need to implement a temporary workaround until we implement the full solution in SPM-3830.

Thus, the goal of this ticket is to implement an API that can be used on the router to retrieve those flags on the spot from the DB primary shard. Since this is a temporary workaround, it does not need to be very performant.