Use correct StartupWMClass in desktop entry

This prevents two entries appearing in the launcher.

Fixes #6593

build/gulpfile.vscode.js

@@ -270,6 +270,7 @@ function prepareDebPackage(arch) {
 	return function () {
 		var desktop = gulp.src('resources/linux/code.desktop', { base: '.' })
 			.pipe(replace('@@NAME_LONG@@', product.nameLong))
+			.pipe(replace('@@NAME_SHORT@@', product.nameShort))
 			.pipe(replace('@@NAME@@', product.applicationName))
 			.pipe(rename('usr/share/applications/' + product.applicationName + '.desktop'));
 
@@ -340,6 +341,7 @@ function prepareRpmPackage(arch) {
 	return function () {
 		var desktop = gulp.src('resources/linux/code.desktop', { base: '.' })
 			.pipe(replace('@@NAME_LONG@@', product.nameLong))
+			.pipe(replace('@@NAME_SHORT@@', product.nameShort))
 			.pipe(replace('@@NAME@@', product.applicationName))
 			.pipe(rename('BUILD/usr/share/applications/' + product.applicationName + '.desktop'));
 

resources/linux/code.desktop

@@ -6,7 +6,7 @@ Exec=/usr/bin/@@NAME@@ %U
 Icon=@@NAME@@
 Type=Application
 StartupNotify=true
-StartupWMClass=@@NAME@@
+StartupWMClass=@@NAME_SHORT@@
 Categories=Utility;TextEditor;Development;IDE;
 MimeType=text/plain;
 Actions=new-window;