[Sb refactor] [demo] Use better default for demo mode

DemoModeConnectionsRepository was using (isConnected = false, isValidated
= false) for its default mobile connectivity model, and doesn't yet
support updating those values via the command line.

This CL just changes the default to be (true, true) so that the icons
properly show up.

Test: manual demo mode
Bug: 238425913
Change-Id: I1c9ade7ed0bd3c278ed38a3b306627a2879fb83e

packages/SystemUI/src/com/android/systemui/statusbar/pipeline/mobile/data/repository/demo/DemoMobileConnectionsRepository.kt

@@ -156,7 +156,8 @@ constructor(
     override val defaultDataSubId = MutableStateFlow(INVALID_SUBSCRIPTION_ID)
 
     // TODO(b/261029387): not yet supported
-    override val defaultMobileNetworkConnectivity = MutableStateFlow(MobileConnectivityModel())
+    override val defaultMobileNetworkConnectivity =
+        MutableStateFlow(MobileConnectivityModel(isConnected = true, isValidated = true))
 
     override fun getRepoForSubId(subId: Int): DemoMobileConnectionRepository {
         val current = connectionRepoCache[subId]?.repo

packages/SystemUI/tests/src/com/android/systemui/statusbar/pipeline/mobile/data/repository/demo/DemoMobileConnectionsRepositoryTest.kt

@@ -89,6 +89,14 @@ class DemoMobileConnectionsRepositoryTest : SysuiTestCase() {
         underTest.startProcessingCommands()
     }
 
+    @Test
+    fun `connectivity - defaults to connected and validated`() =
+        testScope.runTest {
+            val connectivity = underTest.defaultMobileNetworkConnectivity.value
+            assertThat(connectivity.isConnected).isTrue()
+            assertThat(connectivity.isValidated).isTrue()
+        }
+
     @Test
     fun `network event - create new subscription`() =
         testScope.runTest {