Rework member cleanup in RealTimeUrlLookupServiceTest::TearDown()

Avoid spurious dangling ptr warnings by clearing the raw token
fetcher and ensuring the cache manager outlives the rt service.

Bug: 1401495
Change-Id: Ib0fab027859ffea15def13f67edcf6c8b8cbd3b0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4550044


Reviewed-by: thefrog <thefrog@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1147424}