[Backport 2.x][CI][Tests] Add BWC tests for 2.4.0 (opensearch-project#2393)

Signed-off-by: Manasvini B Suryanarayana <manasvis@amazon.com>
(cherry picked from commit 08d0504)
Signed-off-by: Manasvini B Suryanarayana <manasvis@amazon.com>

Author: manasvinibs

bwctest.sh

@@ -13,7 +13,7 @@
 
 set -e
 
-DEFAULT_VERSIONS="osd-2.0.0,osd-2.1.0,osd-2.2.0"
+DEFAULT_VERSIONS="osd-2.0.0,osd-2.1.0,osd-2.2.0,osd-2.3.0"
 
 function usage() {
     echo ""