Fix the bug of losing Wi-Fi certificate when editing

- When the saved certificate is loaded into the UI, the EAP method
spinner will trigger a redundant item selection event to refresh the
certificate to the default value.

- Filter out redundant item selection event of the EAP method spinner.

- Analysis report:
  https://docs.google.com/document/d/1uzyO0NQsT0PVT-ZKbWtDTt4KRXvm3L994MmZTXZ4d5Y/edit?usp=sharing

Bug: 161569880
Test: make RunSettingsRoboTests
ROBOTEST_FILTER=WifiConfigController2Test
Merged-In: I947fb7668ffa7e9ed8c150fe14e6ae9d7a67393c
Change-Id: I00b73b4bfc078aca37396aab4c802a3de64318cf

src/com/android/settings/wifi/WifiConfigController2.java

@@ -164,6 +164,7 @@ public class WifiConfigController2 implements TextWatcher,
     private ScrollView mDialogContainer;
     private Spinner mSecuritySpinner;
     @VisibleForTesting Spinner mEapMethodSpinner;
+    private int mLastShownEapMethod;
     @VisibleForTesting Spinner mEapSimSpinner;    // For EAP-SIM, EAP-AKA and EAP-AKA-PRIME.
     private Spinner mEapCaCertSpinner;
     private Spinner mEapOcspSpinner;
@@ -1057,6 +1058,7 @@ public class WifiConfigController2 implements TextWatcher,
             final int eapMethod = enterpriseConfig.getEapMethod();
             final int phase2Method = enterpriseConfig.getPhase2Method();
             mEapMethodSpinner.setSelection(eapMethod);
+            mLastShownEapMethod = eapMethod;
             showEapFieldsByMethod(eapMethod);
             switch (eapMethod) {
                 case Eap.PEAP:
@@ -1627,7 +1629,11 @@ public class WifiConfigController2 implements TextWatcher,
                 mSsidScanButton.setVisibility(View.GONE);
             }
         } else if (parent == mEapMethodSpinner) {
-            showSecurityFields(/* refreshEapMethods */ false, /* refreshCertificates */ true);
+            final int selectedItemPosition = mEapMethodSpinner.getSelectedItemPosition();
+            if (mLastShownEapMethod != selectedItemPosition) {
+                mLastShownEapMethod = selectedItemPosition;
+                showSecurityFields(/* refreshEapMethods */ false, /* refreshCertificates */ true);
+            }
         } else if (parent == mEapCaCertSpinner) {
             showSecurityFields(/* refreshEapMethods */ false, /* refreshCertificates */ false);
         } else if (parent == mPhase2Spinner