Pause APF filter before starting test

adb shell cmd apf <iface> install requires APF to be paused beforehand.
Resume in tearDown.

Test: atest ApfIntegrationTest
Change-Id: I1b1345a629dc03446ae3b74ab06f40a06085cd28

tests/cts/net/src/android/net/cts/ApfIntegrationTest.kt

@@ -93,6 +93,7 @@ class ApfIntegrationTest {
             ifname = assertNotNull(it.lp.interfaceName)
             true
         }
+        runShellCommandOrThrow("cmd network_stack apf $ifname pause")
     }
 
     @After
@@ -100,6 +101,7 @@ class ApfIntegrationTest {
         if (::networkCallback.isInitialized) {
             cm.unregisterNetworkCallback(networkCallback)
         }
+        runShellCommandOrThrow("cmd network_stack apf $ifname resume")
     }
 
     fun getApfCapabilities(): ApfCapabilities {