Add Elastic Agent 8.19.12 release notes (#12861) (#12965)

* add the 8.19.12 Elastic Agent release notes

* clean up changelog entries

---------

Co-authored-by: ebeahan <7226265+ebeahan@users.noreply.github.com>
Co-authored-by: ebeahan <eric.beahan@elastic.co>
(cherry picked from commit 36294d3)

# Conflicts:
#	changelog/fragments/1770821590-update-otel-components-to-v0.145.0.yaml

Co-authored-by: elastic-vault-github-plugin-prod[bot] <150874479+elastic-vault-github-plugin-prod[bot]@users.noreply.github.com>

Author: mergify[bot]

changelog/8.19.12.asciidoc

@@ -0,0 +1,24 @@
+// begin 8.19.12 relnotes
+
+[[release-notes-8.19.12]]
+==  8.19.12
+
+Review important information about the  8.19.12 release.
+
+[discrete]
+[[enhancements-8.19.12]]
+=== Enhancements
+
+
+* Update OTel Collector components to v0.144.0/v1.50.0. https://github.com/elastic/elastic-agent/pull/12735[#12735]
+
+
+[discrete]
+[[bug-fixes-8.19.12]]
+=== Bug fixes
+
+
+* Adds a missing dependency for Synthetics on wolfi docker image. https://github.com/elastic/elastic-agent/pull/12453[#12453]
+* Ensure otel collector health check requests reuse the TCP connection. https://github.com/elastic/elastic-agent/pull/12517[#12517]
+
+// end 8.19.12 relnotes

changelog/8.19.12.yaml

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+version: 8.19.12
+entries:
+    - kind: bug-fix
+      summary: Adds a missing dependency for Synthetics on wolfi docker image
+      description: ""
+      component: elastic-agent
+      pr:
+        - https://github.com/elastic/elastic-agent/pull/12453
+      issue: []
+      impact: ""
+      action: ""
+      timestamp: 1769621019
+      file:
+        name: 1769621019-synthetics-add-playwright-dependency-on-wolfi.yaml
+        checksum: 2bfe5a207cb383c59b53cd8a304403fce8c8b0e7
+    - kind: bug-fix
+      summary: Ensure otel collector health check requests reuse the TCP connection
+      description: ""
+      component: elastic-agent
+      pr:
+        - https://github.com/elastic/elastic-agent/pull/12517
+      issue: []
+      impact: ""
+      action: ""
+      timestamp: 1769802977
+      file:
+        name: 1769802977-fix-otel-healthcheck.yaml
+        checksum: a68e4673e42829bb088d56675373f0ceb497fd10
+    - kind: enhancement
+      summary: Update OTel Collector components to v0.144.0/v1.50.0
+      description: ""
+      component: elastic-agent
+      pr:
+        - https://github.com/elastic/elastic-agent/pull/12735
+      issue: []
+      impact: ""
+      action: ""
+      timestamp: 1770896223
+      file:
+        name: 1770896223-update-otel-to-01440.yaml
+        checksum: 98f58a388bf39a58b64da82ef8d37960fbcc3773