Fix flaky TeleServices tests causing module errors

Some tests were using reflection to replace static instances but not
resetting the previous values, causing the device to remain in a bad
state. Add a replaceInstance and restoreInstances method to
TelephonyTestBase and have these classes extend it so cleanup can be
done in the @After method.
Fix flaky NotificationMgrTests causing module errors due to incomplete
mocks.
Also revert changes added to help debug b/256244889.

Test: atest TeleServiceTests
Bug: 256244889
Change-Id: Id758e207da862f450d5c90971cb3ea1bd2afe40d
diff --git a/src/com/android/phone/PhoneGlobals.java b/src/com/android/phone/PhoneGlobals.java
index f18535c..abbd816 100644
--- a/src/com/android/phone/PhoneGlobals.java
+++ b/src/com/android/phone/PhoneGlobals.java
@@ -81,7 +81,6 @@
 import java.io.PrintWriter;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
-import java.util.ArrayList;
 import java.util.List;
 
 /**
@@ -889,10 +888,8 @@
 
         boolean dataAllowed;
         boolean notAllowedDueToRoamingOff;
-        List<DataDisallowedReason> reasons = new ArrayList<>();
-        if (phone.getDataNetworkController() != null) {
-            reasons = phone.getDataNetworkController().getInternetDataDisallowedReasons();
-        }
+        List<DataDisallowedReason> reasons = phone.getDataNetworkController()
+                .getInternetDataDisallowedReasons();
         dataAllowed = reasons.isEmpty();
         notAllowedDueToRoamingOff = (reasons.size() == 1
                 && reasons.contains(DataDisallowedReason.ROAMING_DISABLED));
@@ -938,11 +935,7 @@
      * @return whether we have transitioned to dataRoaming
      */
     private boolean dataIsNowRoaming(int subId) {
-        if (getPhone(subId).getServiceState() == null) {
-            return false;
-        } else {
-            return getPhone(subId).getServiceState().getDataRoaming();
-        }
+        return getPhone(subId).getServiceState().getDataRoaming();
     }
 
     private void updateLimitedSimFunctionForDualSim() {
diff --git a/src/com/android/phone/PhoneInterfaceManager.java b/src/com/android/phone/PhoneInterfaceManager.java
index 3f05f0a..7c176ef 100755
--- a/src/com/android/phone/PhoneInterfaceManager.java
+++ b/src/com/android/phone/PhoneInterfaceManager.java
@@ -6804,12 +6804,7 @@
             int phoneId = mSubscriptionController.getPhoneId(subId);
             Phone phone = PhoneFactory.getPhone(phoneId);
             if (phone != null) {
-                boolean retVal;
-                if (phone.getDataSettingsManager() == null) {
-                    retVal = false;
-                } else {
-                    retVal = phone.getDataSettingsManager().isDataEnabled();
-                }
+                boolean retVal = phone.getDataSettingsManager().isDataEnabled();
                 if (DBG) log("isDataEnabled: " + retVal + ", subId=" + subId);
                 return retVal;
             } else {