Remove SELF_LOCK from LiveRecipientCache.

Had the potential to deadlock if accessed inside of a database
transaction.

app/src/main/java/org/thoughtcrime/securesms/recipients/LiveRecipientCache.java

@@ -9,6 +9,7 @@ import androidx.annotation.NonNull;
 
 import org.signal.core.util.concurrent.SignalExecutors;
 import org.signal.core.util.logging.Log;
+import org.thoughtcrime.securesms.crypto.DatabaseSessionLock;
 import org.thoughtcrime.securesms.database.DatabaseFactory;
 import org.thoughtcrime.securesms.database.RecipientDatabase;
 import org.thoughtcrime.securesms.database.RecipientDatabase.MissingRecipientException;
@@ -16,6 +17,7 @@ import org.thoughtcrime.securesms.database.ThreadDatabase;
 import org.thoughtcrime.securesms.database.model.ThreadRecord;
 import org.thoughtcrime.securesms.util.LRUCache;
 import org.thoughtcrime.securesms.util.TextSecurePreferences;
+import org.whispersystems.signalservice.api.SignalSessionLock;
 
 import java.util.ArrayList;
 import java.util.Collection;
@@ -30,14 +32,11 @@ public final class LiveRecipientCache {
   private static final int CACHE_MAX      = 1000;
   private static final int CACHE_WARM_MAX = 500;
 
-  private static final Object SELF_LOCK = new Object();
-
   private final Context                         context;
   private final RecipientDatabase               recipientDatabase;
   private final Map<RecipientId, LiveRecipient> recipients;
   private final LiveRecipient                   unknown;
 
-  @GuardedBy("SELF_LOCK")
   private RecipientId localRecipientId;
   private boolean     warmedUp;
 
@@ -111,7 +110,7 @@ public final class LiveRecipientCache {
   }
 
   @NonNull Recipient getSelf() {
-    synchronized (SELF_LOCK) {
+    try (SignalSessionLock.Lock unused = DatabaseSessionLock.INSTANCE.acquire()) {
       if (localRecipientId == null) {
         UUID   localUuid = TextSecurePreferences.getLocalUuid(context);
         String localE164 = TextSecurePreferences.getLocalNumber(context);