Don't reparse Uri path

I was initially trying to understand why this method was failing due
to an unrelated error [1] so I ended up over-engineering the path
parsing.

We can use the path from the first workspace folder, like we do in
other places in the extension.

[1]: https://github.com/github/vscode-codeql/pull/2104

extensions/ql-vscode/src/local-databases-ui.ts

@@ -403,19 +403,17 @@ export class DatabaseUI extends DisposableObject {
   };
 
   private handleTourDependencies = async (): Promise<void> => {
-    // find workspace root folder
     if (!workspace.workspaceFolders?.length) {
       throw new Error("No workspace folder is open.");
     } else {
-      // find tutorial queries folder
-      const tutorialQueriesPath = Uri.parse(
-        `${workspace.workspaceFolders?.[0].uri}/tutorial-queries`,
+      const tutorialQueriesPath = join(
+        `${workspace.workspaceFolders[0].uri.fsPath}/tutorial-queries`,
       );
       const cli = this.queryServer?.cliServer;
       if (!cli) {
         throw new Error("No CLI server found");
       }
-      await cli.packInstall(tutorialQueriesPath.fsPath);
+      await cli.packInstall(tutorialQueriesPath);
     }
   };