test: de-flake client-cache deployment tests (#87412)
These tests aren't resilient to changes in router behavior after
extensive refactors. What looks to be happening is a race between the
prefetch being issued and the click firing:
1. Cache expires -> refetch prefetch is triggered
2. Click happens while prefetch is in-flight -> route entry is Pending
3. Since no fulfilled cache entry exists, `navigate()` falls through to
`navigateDynamicallyWithNoPrefetch()`
4. This issues a full dynamic request
5. The full dynamic response is favored and skips the loading state
This ensures that we are waiting for network activity to finish before
navigating.
