Remove a lot of dead code.

Resolves #14672

core/util/src/main/java/org/signal/core/util/LinkedBlockingLifoQueue.java

@@ -1,23 +0,0 @@
-package org.signal.core.util;
-
-
-import java.util.concurrent.LinkedBlockingDeque;
-
-public class LinkedBlockingLifoQueue<E> extends LinkedBlockingDeque<E> {
-  @Override
-  public void put(E runnable) throws InterruptedException {
-    super.putFirst(runnable);
-  }
-
-  @Override
-  public boolean add(E runnable) {
-    super.addFirst(runnable);
-    return true;
-  }
-
-  @Override
-  public boolean offer(E runnable) {
-    super.addFirst(runnable);
-    return true;
-  }
-}