Currently, if the app's target SDK is V+, the rate-limit cache is
enabled regardless of whether the kill switch is enabled or not.
This creates problems if there is a need to disable the feature
entirely.
Thus, this change makes the kill switch override the target SDK
level. This is necessary for follow-up changes to enable
the client-side cache and disable the service-side cache
simultaneously.
This change also removes the need of initializing/clearing the
caches when the cache is entirely disabled.
Test: atest FrameworksNetTests:android.net.connectivity.android.net.TrafficStatsTest \
FrameworksNetTests:android.net.connectivity.com.android.server.net.NetworkStatsServiceTest \
CtsNetTestCases:android.net.cts.NetworkStatsBinderTest \
FrameworksNetIntegrationTests:com.android.server.net.integrationtests.NetworkStatsIntegrationTest
Bug: 343260158
Change-Id: I38bdfe00220f59712ca4b095fe4e7a3731320708
24fcc3668a