eng, sync microsoft/typespec#9993 and prepare release 0.43.0 (#3301)

* Initial plan

* update node.js dependencies: sync core to PR #9993, update packages to latest

Co-authored-by: weidongxu-microsoft <53292327+weidongxu-microsoft@users.noreply.github.com>

* prepare release 0.43.0, sync tests, delete loadtesting patch

Co-authored-by: weidongxu-microsoft <53292327+weidongxu-microsoft@users.noreply.github.com>

* core on main

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: weidongxu-microsoft <53292327+weidongxu-microsoft@users.noreply.github.com>
Co-authored-by: Weidong Xu <weidxu@microsoft.com>

Author: Copilot

core

@@ -1,5 +1,11 @@
 # Release History
 
+## 0.43.0 (2026-03-12)
+
+Compatible with compiler 1.10.0.
+
+- Updated package dependencies to the latest versions.
+
 ## 0.42.0 (2026-03-09)
 
 Compatible with compiler 1.9.0.