Don't collect open-file telemetry on the syntax server

It's throwing an exception (since there's no program from which to
retrieve the SourceFile) and there's no reason to fix it since the
same files are open in the semantic server.

src/server/editorServices.ts

@@ -2123,7 +2123,7 @@ namespace ts.server {
         }
 
         private telemetryOnOpenFile(scriptInfo: ScriptInfo): void {
-            if (!this.eventHandler || !scriptInfo.isJavaScript() || !addToSeen(this.allJsFilesForOpenFileTelemetry, scriptInfo.path)) {
+            if (this.syntaxOnly || !this.eventHandler || !scriptInfo.isJavaScript() || !addToSeen(this.allJsFilesForOpenFileTelemetry, scriptInfo.path)) {
                 return;
             }