Remove unnecessary sleep workaround in test

Previously, when we start VPN, even if the onAvailable callback fires,
the VPN UID ranges are not yet configured. So, we needed to have a sleep
to wait some time.

But this is fixed now.
When VPN register a network agent, VPN send EVENT_REGISTER_NETWORK_AGENT
with CONNECTING state and EVENT_NETWORK_INFO_CHANGED with CONNECTED state to ConnectivityService.

In the process of the first event, ConnectivityService configures VPN
UID ranges. And in the process of the second event, ConnectivityService
fires onAvailable callback.
Network agent makes sure the second event is sent after the first event.

So, when onAvailable callback fires, VPN UID ranges are configured.

Also, I have run "atest HostsideVpnTests --iterations 30" and confirmed
tests do not fail.

Test: atest HostsideVpnTests --iterations 30
Change-Id: I9cc908e7a1c0ea7b5bec08571f4e1028e05dfc56
diff --git a/tests/cts/hostside/app/src/com/android/cts/net/hostside/VpnTest.java b/tests/cts/hostside/app/src/com/android/cts/net/hostside/VpnTest.java
index dc67c70..dd8b523 100755
--- a/tests/cts/hostside/app/src/com/android/cts/net/hostside/VpnTest.java
+++ b/tests/cts/hostside/app/src/com/android/cts/net/hostside/VpnTest.java
@@ -378,10 +378,6 @@
         if (mNetwork == null) {
             fail("VPN did not become available after " + TIMEOUT_MS + "ms");
         }
-
-        // Unfortunately, when the available callback fires, the VPN UID ranges are not yet
-        // configured. Give the system some time to do so. http://b/18436087 .
-        try { Thread.sleep(3000); } catch(InterruptedException e) {}
     }
 
     private void stopVpn() {