Restore presubmit of testSetOemNetworkPreferenceForTestOnlyPref

Mark fixed this test in aosp/2709233

Bug: 295829521
Test: Dashboard will stop showing this failure
Change-Id: I439d4b65b2fc5981af924fb1f1155273bdd52e7a
diff --git a/tests/cts/net/src/android/net/cts/ConnectivityManagerTest.java b/tests/cts/net/src/android/net/cts/ConnectivityManagerTest.java
index e978664..66e4799 100644
--- a/tests/cts/net/src/android/net/cts/ConnectivityManagerTest.java
+++ b/tests/cts/net/src/android/net/cts/ConnectivityManagerTest.java
@@ -2744,7 +2744,6 @@
      */
     @AppModeFull(reason = "Instant apps cannot create test networks")
     @Test
-    @SkipMainlinePresubmit(reason = "Out of SLO flakiness")
     public void testSetOemNetworkPreferenceForTestOnlyPref() throws Exception {
         // Cannot use @IgnoreUpTo(Build.VERSION_CODES.R) because this test also requires API 31
         // shims, and @IgnoreUpTo does not check that.