Flaky test: `Custom RPC history deletes a custom RPC`

### What is this about?

[View logs](https://github.com/MetaMask/metamask-extension/actions/runs/15338121083/job/43159418120)
```js
TimeoutError: Waiting for element to be located By(xpath, //h4[contains(text(), "Select a network")])
Wait timed out after 10008ms
at /__w/metamask-extension/metamask-extension/node_modules/selenium-webdriver/lib/webdriver.js:929:22
at process.processTicksAndRejections (node:internal/process/task_queues:105:5)
```

### Scenario

_No response_

### Design

_No response_

### Technical Details

_No response_

### Threat Modeling Framework

_No response_

### Acceptance Criteria

_No response_

### Stakeholder review needed before the work gets merged

- [ ] Engineering (needed in most cases)
- [ ] Design
- [ ] Product
- [ ] QA (automation tests are required to pass before merging PRs but not all changes are covered by automation tests - please review if QA is needed beyond automation tests)
- [ ] Security
- [ ] Legal
- [ ] Marketing
- [ ] Management (please specify)
- [ ] Other (please specify)

### References

_No response_

Start with the linked GitHub Actions logs and the `Custom RPC history deletes a custom RPC` test scenario, focusing on the Selenium timeout for `Select a network`. Trace the test entry point and the surrounding custom RPC history flow; done means identifying and addressing the flakiness so the test passes reliably.

Written by the indexing model from the issue text.