[release/v1.5] remove metrics that are not there (#2146)

(cherry picked from commit f04b78f)

Co-authored-by: mattdurham <[email protected]>

docs/sources/reference/components/prometheus/prometheus.write.queue.md

@@ -166,10 +166,6 @@ They generally behave the same, but there are likely edge cases where they diffe
   of send calls to remote storage.
 * `prometheus_remote_storage_queue_highest_sent_timestamp_seconds` (gauge):
   Unix timestamp of the latest WAL sample successfully sent by a queue.
-* `prometheus_remote_storage_samples_pending` (gauge): The number of samples
-  pending in shards to be sent to remote storage.
-* `prometheus_remote_storage_exemplars_pending` (gauge): The number of
-  exemplars pending in shards to be sent to remote storage.
 * `prometheus_remote_storage_samples_in_total` (counter): Samples read into
   remote storage.
 * `prometheus_remote_storage_exemplars_in_total` (counter): Exemplars read into