Fix static / version based BWC tests (elastic#1456)

With the leniency in Version.java we missed to really setup BWC
testing for static indices. This change brings back the testing and adds
missing bwc indices.

Relates to elastic#24732

server/src/main/java/org/elasticsearch/persistent/PersistentTasksCustomMetaData.java

@@ -196,7 +196,7 @@ public long getNumberOfTasksOnNode(String nodeId, String taskName) {
 
     @Override
     public Version getMinimalSupportedVersion() {
-        return Version.V_5_4_0_UNRELEASED;
+        return Version.V_5_4_0;
     }
 
     @Override