extension: stop setting "preview" for v0.43.0

v0.43.0 is our first pre-release version that replaces
the nightly extension. Pre-release is built from the master
branch. Previously we set the preview' field because
the nightly extension is built from the master and
golang.go-nightly is a preview extension in our
definition. golang.go is not a preview extension
so let's unset this field.

Nightly extension publishing is paused.

And add a CHANGELOG entry for v0.43.0.
For pre-release versions, we will skip CHANGELOG addition.
But, it's good to announce the first pre-release version
and mention the deprecation of nightly.

For #1935

Change-Id: I326963818aa3bd7723bbdf69d5b747f57210b5c1
Reviewed-on: https://go-review.googlesource.com/c/vscode-go/+/607756
Reviewed-by: Robert Findley <[email protected]>
Commit-Queue: Hyang-Ah Hana Kim <[email protected]>
kokoro-CI: kokoro <[email protected]>

Author: hyangah

extension/CHANGELOG.md

@@ -1,3 +1,7 @@
+## v0.43.0 - 22 Aug, 2024 (pre-release)
+
+This is the [pre-release version](https://code.visualstudio.com/api/working-with-extensions/publishing-extension#prerelease-extensions) of v0.44. The nightly (golang.go-nightly) extension will be deprecated in favor of the pre-release version.
+
 ## v0.42.0 - 17 Jul, 2024
 
 A comprehensive list of changes can be found in the complete [commit history](https://github.com/golang/vscode-go/compare/v0.42.0...v0.41.4).

extension/package.json

@@ -2,7 +2,6 @@
   "name": "go",
   "displayName": "Go",
   "version": "0.43.0-dev",
-  "preview": true,
   "publisher": "golang",
   "description": "Rich Go language support for Visual Studio Code",
   "author": {