test: harden multi-root e2e startup wait

Author: roomote

apps/vscode-e2e/src/suite/multi-root-read-file-content.test.ts

@@ -13,8 +13,8 @@ suite("Multi-root readFileContent repro", function () {
 
 	test("should read a file that exists only in the secondary workspace root", async () => {
 		await waitFor(() => (vscode.workspace.workspaceFolders?.length ?? 0) >= 2, {
-			timeout: 15_000,
-			interval: 100,
+			timeout: 60_000,
+			interval: 250,
 		})
 
 		const primaryWorkspace = vscode.workspace.workspaceFolders?.[0]