Check for first api level before turn on eBPF

The api check will ensure the device is running 4.9 or above kernel and
is shipped originally with P release. Also add some test to make sure
eligible devices always have eBPF turned on.

Test: ./netd_integration_test
Bug: 79408692
Change-Id: Ief56a95aab892c92276a5b4ac74b03f9f32f5b54
Merged-In: Ief56a95aab892c92276a5b4ac74b03f9f32f5b54
(cherry picked from aosp commit 837ddfcb)