private void filterField(String f) {
        for (RankProfile rp : rankProfileRegistry.rankProfilesOf(schema)) {
            rp.filterFields().add(f);
        }
    }
Takes the fields and indexes that are of type rank filter, and stores those names on all rank profiles

@author Vegard Havdal
config-model/src/main/java/com/yahoo/schema/processing/FilterFieldNames.java