refactor: remove rsync postinstall

Author: Joe Previte

ci/build/build-release.sh

@@ -146,7 +146,6 @@ EOF
   # Include global extension dependencies as well.
   rsync "$VSCODE_SRC_PATH/extensions/package.json" "$VSCODE_OUT_PATH/extensions/package.json"
   rsync "$VSCODE_SRC_PATH/extensions/yarn.lock" "$VSCODE_OUT_PATH/extensions/yarn.lock"
-  rsync "$VSCODE_SRC_PATH/extensions/postinstall.js" "$VSCODE_OUT_PATH/extensions/postinstall.js"
 
   pushd "$VSCODE_OUT_PATH"
   symlink_asar