Remove unreleased 7.1.2 version constant (#43629)

This was breaking BWC tests as the presence of the constant implied 7.1.2 was released

server/src/main/java/org/elasticsearch/Version.java

@@ -51,7 +51,6 @@ public class Version implements Comparable<Version>, ToXContentFragment {
     public static final Version V_7_0_1 = new Version(7000199, org.apache.lucene.util.Version.LUCENE_8_0_0);
     public static final Version V_7_1_0 = new Version(7010099, org.apache.lucene.util.Version.LUCENE_8_0_0);
     public static final Version V_7_1_1 = new Version(7010199, org.apache.lucene.util.Version.LUCENE_8_0_0);
-    public static final Version V_7_1_2 = new Version(7010299, org.apache.lucene.util.Version.LUCENE_8_0_0);
     public static final Version V_7_2_0 = new Version(7020099, org.apache.lucene.util.Version.LUCENE_8_0_0);
     public static final Version V_7_2_1 = new Version(7020199, org.apache.lucene.util.Version.LUCENE_8_0_0);
     public static final Version V_7_3_0 = new Version(7030099, org.apache.lucene.util.Version.LUCENE_8_1_0);