DO NOT MERGE IpConnectivityMetrics: rate limit ApfProgramEvents

This patch uses the previously introduced TokenBucket to rate limit
ApfProgramEvents, still allowing for burst of ApfProgramEvents when a
new interface is set up (due to ipv4 provisioning, multicast lock, ipv6 RAs
triggering new APF program events in short amounts of time).

Test: new test in IpConnectivityMetricsTest
Bug: 1550402

(cherry picked from commit 811c4cec757f994551467de6dce3b5208e4ac601)

Change-Id: Ibe41e9a76db36ea502697a5f19fc0d91c40a3087
1 file changed
tree: 4747999c6d0a5f34e0cbda370eaaf74bf6e9d559
  1. core/
  2. services/
  3. tests/