SimpleCache: fix lifetime of AppStatusListener on Android.

Previously, NetworkContext would pass SimpleBackendImpl creation
a pointer to a status listener it owns.  While NetworkContext
normally owns both the cache and the app status listener, the
cache backend creation is an asynchronous process, so if the
network context was destroyed before the cache creation was
complete, and ownership of fresh cache backend handed over to
NetworkContext, the backend could end up using a dangling
pointer to AppStatusListener.

This changes to pass in a getter RepeatingCallback instead,
which checks for NetworkContext destruction before returning
the pointer.

Re-enable some tests that were flaking because of this.

Bug: 1492976, 1311000, 1492127, 1492124, 1492118, 1493317
Change-Id: Ic2062c18d9e8a13470ee9d817ba81b49ce60c697
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4947433
Reviewed-by: Kenichi Ishibashi <bashi@chromium.org>
Commit-Queue: Maks Orlovich <morlovich@chromium.org>
Reviewed-by: Christian Dullweber <dullweber@chromium.org>
Reviewed-by: Peter Beverloo <peter@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1211454}