Update 8.19.0.asciidoc (#132754)

Reverting change based on the comment.

Author: ppf2

docs/reference/release-notes/8.19.0.asciidoc

@@ -539,17 +539,4 @@ Snapshot/Restore::
 * Upgrade AWS Java SDK to 2.31.78 {es-pull}131050[#131050]
 * Upgrade AWS SDK to v1.12.746 {es-pull}122431[#122431]
 
-[discrete]
-[[known-issues-8.19.0]]
-=== Known issues
-
-* An [optimization](https://github.com/elastic/elasticsearch/pull/125403) introduced in 8.19.0 contains a [bug](https://github.com/elastic/elasticsearch/pull/132597) that causes merges to fail for shrunk TSDB and LogsDB indices.
-  
-  Possible *temporary* workarounds include:
-  * Configure the ILM policy to not perform force merges after shrinking TSDB or LogsDB indices.
-  * Add `-Dorg.elasticsearch.index.codec.tsdb.es819.ES819TSDBDocValuesConsumer.enableOptimizedMerge=false` as a Java system property to all data nodes in the cluster and perform a rolling restart.
-    * *Important:* Remove this property when upgrading to the fixed version to re-enable merge optimization. Otherwise, merges will be slower.  
-
-The bug is addressed in version 8.19.2. 
-