Prune changelogs after 8.16.6 release

docs/changelog/123890.yaml

@@ -1,5 +0,0 @@
-pr: 123890
-summary: Do not let `ShardBulkInferenceActionFilter` unwrap / rewrap ESExceptions
-area: Search
-type: bug
-issues: []

docs/changelog/124544.yaml

@@ -1,5 +0,0 @@
-pr: 124544
-summary: Bump nimbus-jose-jwt to 10.0.2
-area: Security
-type: upgrade
-issues: []

docs/changelog/124732.yaml

@@ -1,6 +0,0 @@
-pr: 124732
-summary: Prevent rare starvation bug when using scaling `EsThreadPoolExecutor` with empty core pool size.
-area: Infra/Core
-type: bug
-issues:
-  - 124667