Fix keepalive don't get removed when lower layer error

Currently, if the lower layer, e.g. wifi, didn't successfully
start keepalive by any reason. Due to the startedState changed
to NOT_STARTED first, the logic inside stop() will skip the
removing process and cause leak.

Thus, moving the changing of startedState to proper place first
to unblock subsequent changes first.

Bug: 123988249
Bug: 129371366
Test: atest FrameworksNetTests
Change-Id: I4bba01bacc80e1dac2023ef831b5ade5501894e4

services/core/java/com/android/server/connectivity/KeepaliveTracker.java

@@ -480,7 +480,6 @@ public class KeepaliveTracker {
             }
         } else {
             // Keepalive successfully stopped, or error.
-            ki.mStartedState = KeepaliveInfo.NOT_STARTED;
             if (reason == SUCCESS) {
                 // The message indicated success stopping : don't call handleStopKeepalive.
                 if (DBG) Log.d(TAG, "Successfully stopped keepalive " + slot + " on " + nai.name());
@@ -490,6 +489,7 @@ public class KeepaliveTracker {
                 handleStopKeepalive(nai, slot, reason);
                 if (DBG) Log.d(TAG, "Keepalive " + slot + " on " + nai.name() + " error " + reason);
             }
+            ki.mStartedState = KeepaliveInfo.NOT_STARTED;
         }
     }