Report disallowed metric labels as "other"
To keep amount of metric labels small, we deny unwanted labels and only keep those which are interesting to have in the telemetry data. However, previously when metric had a label that was not allowed, it was simply dropped.
This is skewing the data, when presenting total numbers as sum of all measurements (or duration histogram) those dropped measurements must be included. This patch changes the behavior, it is now measured with label value of "Other".
The patch also adds one more metric which is amount of loaded record ids into authorizer cache so we can keep an eye on the rate.