[Azure.AI.Projects] Update CHANGELOG.md release date (Azure#48492)

* Update CHANGELOG.md release date

* Removed unused sections

Author: trangevi

sdk/ai/Azure.AI.Projects/CHANGELOG.md

@@ -1,18 +1,12 @@
 # Release History
 
-## 1.0.0-beta.4 (Unreleased)
-
-### Features Added
-
-### Breaking Changes
+## 1.0.0-beta.4 (2025-02-28)
 
 ### Bugs Fixed
 
 * Fixed deserialization failure for AzureBlobStorage connection [issue](https://github.com/Azure/azure-sdk-for-net/issues/47874)
 * Fixed a bug on deserialization of RunStepDeltaFileSearchToolCall [issue](https://github.com/Azure/azure-sdk-for-net/issues/48333)
 
-### Other Changes
-
 ## 1.0.0-beta.3 (2025-01-22)
 
 ### Bugs Fixed