Elasticsearch: Discontinue EOL versions 7.2 and 7.3 support

Remove support for elasticsearch versions 7.2 and 7.3, as both became
EOL recently [1].

[1] https://www.elastic.co/support/eol

Change-Id: Ib48900ce4c5530023a5425d1fe3e65e03f17c933
diff --git a/java/com/google/gerrit/elasticsearch/ElasticVersion.java b/java/com/google/gerrit/elasticsearch/ElasticVersion.java
index bba1577..5e72780 100644
--- a/java/com/google/gerrit/elasticsearch/ElasticVersion.java
+++ b/java/com/google/gerrit/elasticsearch/ElasticVersion.java
@@ -18,8 +18,6 @@
 import java.util.regex.Pattern;
 
 public enum ElasticVersion {
-  V7_2("7.2.*"),
-  V7_3("7.3.*"),
   V7_4("7.4.*"),
   V7_5("7.5.*"),
   V7_6("7.6.*"),
diff --git a/javatests/com/google/gerrit/elasticsearch/ElasticContainer.java b/javatests/com/google/gerrit/elasticsearch/ElasticContainer.java
index e8cf3e9..8cd09e6 100644
--- a/javatests/com/google/gerrit/elasticsearch/ElasticContainer.java
+++ b/javatests/com/google/gerrit/elasticsearch/ElasticContainer.java
@@ -39,10 +39,6 @@
 
   private static String getImageName(ElasticVersion version) {
     switch (version) {
-      case V7_2:
-        return "blacktop/elasticsearch:7.2.1";
-      case V7_3:
-        return "blacktop/elasticsearch:7.3.2";
       case V7_4:
         return "blacktop/elasticsearch:7.4.2";
       case V7_5:
diff --git a/javatests/com/google/gerrit/elasticsearch/ElasticVersionTest.java b/javatests/com/google/gerrit/elasticsearch/ElasticVersionTest.java
index 1ec8a5d..508dc84 100644
--- a/javatests/com/google/gerrit/elasticsearch/ElasticVersionTest.java
+++ b/javatests/com/google/gerrit/elasticsearch/ElasticVersionTest.java
@@ -22,12 +22,6 @@
 public class ElasticVersionTest {
   @Test
   public void supportedVersion() throws Exception {
-    assertThat(ElasticVersion.forVersion("7.2.0")).isEqualTo(ElasticVersion.V7_2);
-    assertThat(ElasticVersion.forVersion("7.2.1")).isEqualTo(ElasticVersion.V7_2);
-
-    assertThat(ElasticVersion.forVersion("7.3.0")).isEqualTo(ElasticVersion.V7_3);
-    assertThat(ElasticVersion.forVersion("7.3.1")).isEqualTo(ElasticVersion.V7_3);
-
     assertThat(ElasticVersion.forVersion("7.4.0")).isEqualTo(ElasticVersion.V7_4);
     assertThat(ElasticVersion.forVersion("7.4.1")).isEqualTo(ElasticVersion.V7_4);