locksettings: clean up logging of cached GK password expiration

When a cached GK password expires, use a much clearer log message.
Also, don't log anything if the GK password was already explicitly
removed by LockSettingsService.removeGatekeeperPasswordHandle().

Bug: 268526331
Change-Id: I734c9115bd8ea0a44ed6c03754e87341848a00f5
Merged-In: I734c9115bd8ea0a44ed6c03754e87341848a00f5
(cherry picked from commit 070e3d6ce3)

services/core/java/com/android/server/locksettings/LockSettingsService.java

@@ -2728,8 +2728,11 @@ public class LockSettingsService extends ILockSettings.Stub {
         final long finalHandle = handle;
         mHandler.postDelayed(() -> {
             synchronized (mGatekeeperPasswords) {
-                Slog.d(TAG, "Removing handle: " + finalHandle);
-                mGatekeeperPasswords.remove(finalHandle);
+                if (mGatekeeperPasswords.get(finalHandle) != null) {
+                    Slogf.d(TAG, "Cached Gatekeeper password with handle %016x has expired",
+                            finalHandle);
+                    mGatekeeperPasswords.remove(finalHandle);
+                }
             }
         }, GK_PW_HANDLE_STORE_DURATION_MS);