Update CHANGELOG-EE.md for 12.3.4-ee

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CHANGELOG-EE.md

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+## 12.3.4
+
+### Fixed (2 changes)
+
+- Fix replies to service desk emails for projects with issue access as Only Project Members. !17401
+- Geo: LFS not being synced. !17633
+
+
 ## 12.3.2
 ### Security (2 changes)

ee/changelogs/unreleased/31815-service-desk-email-rejections.yml

----
-title: Fix replies to service desk emails for projects with issue access as Only Project Members
-merge_request: 17401
-author:
-type: fixed

ee/changelogs/unreleased/32696-geo-lfs-not-being-synced.yml

----
-title: 'Geo: LFS not being synced'
-merge_request: 17633
-author:
-type: fixed