add CHANGELOG entry

CHANGELOG.md

@@ -17,6 +17,7 @@
 * [CHANGE] Ingester: Change `-initial-delay` for circuit breakers to begin when the first request is received, rather than at breaker activation. #9842
 * [CHANGE] Query-frontend: apply query pruning before query sharding instead of after. #9913
 * [CHANGE] Ingester: remove experimental flags `-ingest-storage.kafka.ongoing-records-per-fetch` and `-ingest-storage.kafka.startup-records-per-fetch`. They are removed in favour of `-ingest-storage.kafka.max-buffered-bytes`. #9906
+* [CHANGE] Ingester: Replace `cortex_discarded_samples_total` label from `sample-out-of-bounds` to `sample-timestamp-too-old`. #9885
 * [FEATURE] Querier: add experimental streaming PromQL engine, enabled with `-querier.query-engine=mimir`. #9367 #9368 #9398 #9399 #9403 #9417 #9418 #9419 #9420 #9482 #9504 #9505 #9507 #9518 #9531 #9532 #9533 #9553 #9558 #9588 #9589 #9639 #9641 #9642 #9651 #9664 #9681 #9717 #9719 #9724 #9874
 * [FEATURE] Distributor: Add support for `lz4` OTLP compression. #9763
 * [FEATURE] Query-frontend: added experimental configuration options `query-frontend.cache-errors` and `query-frontend.results-cache-ttl-for-errors` to allow non-transient responses to be cached. When set to `true` error responses from hitting limits or bad data are cached for a short TTL. #9028