fix: flaky Stripe test timeouts in payment-details.spec.ts

[ethrealSpectre]

1) Problem

The test allows connecting a bank account was failing in CI with a 60s timeout. The locator getByLabel("Test Institution") was stuck waiting for an element that does not exist in the current Stripe test mode UI.

2) Solution

• Reliable Locator: Replaced the broken label selector with a deterministic Search-and-Select workflow (Search "Test" -> Click "Test (Non-OAuth)").
• Robustness: Added explicit timeout: 60000 to Stripe iframe assertions to handle slow loading in CI.
• Speed: Switched from UI-based menu navigation to direct page.goto("/settings/administrator/billing").

3) Screenshot

(No visual changes, purely test fix. Passing test output serves as verification.)

4) AI Disclosure

This PR was generated by an AI assistant.