build: Remove preview flag. (#1592)

Author: jdneo

package.json

@@ -11,7 +11,7 @@
         "url": "https://github.com/Microsoft/vscode-java-test/issues"
     },
     "homepage": "https://github.com/Microsoft/vscode-java-test",
-    "preview": true,
+    "preview": false,
     "icon": "resources/logo.png",
     "keywords": [
         "java",