[cc] Fix dangling ptr in ScopedUIResource

A test was failing with dangling pointer detection because the
FakeScopedUIResource destructor was accessing a dangling
ui_resource_manager_ pointer after the UIResourceManager was destroyed
during test cleanup.

Explicitly destroying ui_resource_ in DeleteAndEndTest() before calling
EndTest() ensures proper destruction order.

Bug: 40212619
Change-Id: If68f1811245a44445d32a8ae281df494955088fc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6692518
Commit-Queue: Sam Fortiner <samfort@microsoft.com>
Reviewed-by: Vladimir Levin <vmpstr@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1482324}