Fix InternalEngineTests

Author: albertzaharovits

server/src/test/java/org/elasticsearch/index/engine/InternalEngineTests.java

@@ -10,7 +10,6 @@
 package org.elasticsearch.index.engine;
 
 import com.carrotsearch.randomizedtesting.generators.RandomNumbers;
-
 import org.apache.logging.log4j.Level;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -2578,10 +2577,10 @@ public boolean mergeCompleted() {
         public void append(LogEvent event) {
             final String formattedMessage = event.getMessage().getFormattedMessage();
             if (event.getLevel() == Level.TRACE && event.getMarker().getName().contains("[index][0]")) {
-                if (formattedMessage.startsWith("merge thread")) {
+                if (formattedMessage.startsWith("merge task")) {
                     messages.add(formattedMessage);
                 } else if (event.getLoggerName().endsWith(".MS")
-                    && formattedMessage.contains("MS: merge thread")
+                    && formattedMessage.contains("MS: merge task")
                     && formattedMessage.endsWith("end")) {
                         luceneMergeSchedulerEnded.set(true);
                     }
@@ -2616,14 +2615,14 @@ public void testMergeThreadLogging() throws Exception {
                 });
 
                 assertBusy(() -> {
-                    List<String> threadMsgs = mockAppender.messages().stream().filter(line -> line.startsWith("merge thread")).toList();
+                    List<String> threadMsgs = mockAppender.messages().stream().filter(line -> line.startsWith("merge task")).toList();
                     assertThat("messages:" + threadMsgs, threadMsgs.size(), greaterThanOrEqualTo(3));
                     assertThat(
                         threadMsgs,
                         containsInRelativeOrder(
-                            matchesRegex("^merge thread .* start$"),
-                            matchesRegex("^merge thread .* merge segment.*$"),
-                            matchesRegex("^merge thread .* end$")
+                            matchesRegex("^merge task .* start$"),
+                            matchesRegex("^merge task .* merge segment.*$"),
+                            matchesRegex("^merge task .* end$")
                         )
                     );
                     assertThat(mockAppender.mergeCompleted(), is(true));