Bump versions after 7.17.8 release

.ci/bwcVersions

@@ -57,6 +57,7 @@ BWC_VERSION:
   - "7.17.6"
   - "7.17.7"
   - "7.17.8"
+  - "7.17.9"
   - "8.0.0"
   - "8.0.1"
   - "8.1.0"

.ci/snapshotBwcVersions

@@ -1,5 +1,5 @@
 BWC_VERSION:
-  - "7.17.8"
+  - "7.17.9"
   - "8.5.4"
   - "8.6.0"
   - "8.7.0"

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

@@ -105,6 +105,7 @@ public class Version implements Comparable<Version>, ToXContentFragment {
     public static final Version V_7_17_6 = new Version(7_17_06_99, org.apache.lucene.util.Version.LUCENE_8_11_1);
     public static final Version V_7_17_7 = new Version(7_17_07_99, org.apache.lucene.util.Version.LUCENE_8_11_1);
     public static final Version V_7_17_8 = new Version(7_17_08_99, org.apache.lucene.util.Version.LUCENE_8_11_1);
+    public static final Version V_7_17_9 = new Version(7_17_09_99, org.apache.lucene.util.Version.LUCENE_8_11_1);
     public static final Version V_8_0_0 = new Version(8_00_00_99, org.apache.lucene.util.Version.LUCENE_9_0_0);
     public static final Version V_8_0_1 = new Version(8_00_01_99, org.apache.lucene.util.Version.LUCENE_9_0_0);
     public static final Version V_8_1_0 = new Version(8_01_00_99, org.apache.lucene.util.Version.LUCENE_9_0_0);