Connectivity metrics: log DnsEvents in-band

This patch changes how DnsEvents are logged in IpConnectivityMetrics.
The following changes are made:
 - DnsEventBatch are not logged after 100 queries on the same network
    - this allows to merge DnsEvent and DnsEventBatch into one class
 - DnsEventBatch are not logged after a network disconnect
    - this allows to remove the NetworkCallback
 - DnsEvent are now logged similarly to ConnectStats when statistics are
   flushed, in a direct call from IpConnectivityMetrics into
   NetdEventListenerService, in a direct call from IpConnectivityMetrics
   into NetdEventListenerService.
    - this allows to remove the Parcelable implementation of DnsEvent
 - transports information is added to DnsEvent.

Test: - simplified NetdEventListenerServiceTest covering dns logging
      - updated IpConnectivityEventBuilderTest
      - updated IpConnectivityMetricsTest
      - $ runtest frameworks-net passes
      - manually verified $ adb shell dumpsys connmetrics list proto
Bug: 34901696
Change-Id: I4fcd0ad7a7b85d587647f471a90c1e53a18fc95a
Merged-In: Ia4b33fd4212741152662a2adbb0533bd1b4902ee

(cherry picked from commit 0699cf98042a64e41ee076c464eb115a6579be08)
diff --git a/tests/net/java/com/android/server/connectivity/IpConnectivityMetricsTest.java b/tests/net/java/com/android/server/connectivity/IpConnectivityMetricsTest.java
index 68786d0..fd81c90 100644
--- a/tests/net/java/com/android/server/connectivity/IpConnectivityMetricsTest.java
+++ b/tests/net/java/com/android/server/connectivity/IpConnectivityMetricsTest.java
@@ -138,6 +138,7 @@
     }
 
     @SmallTest
+    // TODO: add NetdEventListenerService coverage too
     public void testEndToEndLogging() {
         // TODO: instead of comparing textpb to textpb, parse textpb and compare proto to proto.
         IpConnectivityLog logger = new IpConnectivityLog(mService.impl);
@@ -177,7 +178,7 @@
             logger.log(ev);
         }
 
-        String want = joinLines(
+        String want = String.join("\n",
                 "dropped_events: 0",
                 "events <",
                 "  if_name: \"\"",
@@ -279,7 +280,7 @@
                 "    router_lifetime: 2000",
                 "  >",
                 ">",
-                "version: 2");
+                "version: 2\n");
 
         verifySerialization(want, getdump("flush"));
     }