Fix TranslogTests.testTotalTests when n=0 (#65632)

When n=0 in TranslogTests.testTotalTests we never update earliestLastModifiedAge so it fails comparison with default value of total.getEarliestLastModifiedAge() which is 0.
In this change we always check this special case and then select n>0

Closes #65629

server/src/test/java/org/elasticsearch/index/translog/TranslogTests.java

@@ -528,9 +528,15 @@ public void testUncommittedOperations() throws Exception {
     }
 
     public void testTotalTests() {
-        final TranslogStats total =
-            new TranslogStats();
-        final int n = randomIntBetween(0, 16);
+        final TranslogStats total = new TranslogStats();
+
+        assertThat(total.estimatedNumberOfOperations(), equalTo(0));
+        assertThat(total.getTranslogSizeInBytes(), equalTo(0L));
+        assertThat(total.getUncommittedOperations(), equalTo(0));
+        assertThat(total.getUncommittedSizeInBytes(), equalTo(0L));
+        assertThat(total.getEarliestLastModifiedAge(), equalTo(0L));
+
+        final int n = randomIntBetween(1, 16);
         final List<TranslogStats> statsList = new ArrayList<>(n);
         long earliestLastModifiedAge = Long.MAX_VALUE;
         for (int i = 0; i < n; i++) {