Selected filters not persisted to BE in Geo secondaries

We currently persist filters and sorting options to UserPreference in the GET request for that resource.

This doesn't work in Geo secondaries because the DB is read only.

Updates to the DB should be done in a separate POST / PUT request.

This is happening to the issues/ MRs discussion filter (all activity / comments only / history only) and also roadmap_epics_state and epics_sort in EE.

This also applies to fields we plan to save in the backend: https://gitlab.com/gitlab-org/gitlab-ce/issues/50352