Quarantine RoutingTest.NavigationLock_OverlappingNavigationsCancelExistingNavigations_PushState

## Failing Test(s)

- `Microsoft.AspNetCore.Components.E2ETest.Tests.RoutingTest.NavigationLock_OverlappingNavigationsCancelExistingNavigations_PushState`

This test is inherited (not overridden) by `Microsoft.AspNetCore.Components.E2ETest.ServerExecutionTests.ServerRoutingTest`, so quarantining the base method also covers that subclass instance.

## Failure data

Combined failures across `main`-branch CI (Source A) and merged-PR CI (Source B) over the past 30 days: **44 total failures** (36 from Source A, 8 from Source B).

Representative error:
```
OpenQA.Selenium.BrowserAssertFailedException : Xunit.Sdk.EqualException
at Microsoft.AspNetCore.E2ETesting.WaitAssert.WaitAssertCore(...)
at Microsoft.AspNetCore.E2ETesting.WaitAssert.Equal[T](IWebDriver driver, T expected, Func`1 actual)
at Microsoft.AspNetCore.Components.E2ETest.Tests.RoutingTest.NavigationLock_OverlappingNavigationsCancelExistingNavigations_PushState()
```

This is a `Browser.Equal` timing assertion failure consistent with intermittent flakiness in navigation-lock/browser-history interaction timing, not a consistent regression (`is_consistent_regression: false` in the injected Source A data).

## Why quarantine

- Not currently quarantined (no `[QuarantinedTest]` attribute present).
- Never previously quarantined per `git log --follow -p -G 'QuarantinedTest'` history of this file (only one matching commit, the test's original introduction in #42638).
- Not flagged as a consistent regression.
- Failure count (44) well above the 2-failure threshold for Case A quarantine.

This issue tracks stabilizing the test before it can be unquarantined.

> Generated by [Daily Test Quarantine Management](https://github.com/dotnet/aspnetcore/actions/runs/32241253262) · auto · 341.3 AIC · ⌖ 10.4 AIC · ⊞ 4.2K · [◷](https://github.com/search?q=repo%3Adotnet%2Faspnetcore+is%3Aissue+%22gh-aw-workflow-call-id%3A+dotnet%2Faspnetcore%2Ftest-quarantine%22&type=issues)