Adjust version on ingest processor exception

The dedicated ingest processor exception was backported to 7.5. This
commit updates the version in the 7.x branch.

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

@@ -1041,7 +1041,7 @@ private enum ElasticsearchExceptionHandle {
                 org.elasticsearch.ingest.IngestProcessorException.class,
                 org.elasticsearch.ingest.IngestProcessorException::new,
                 157,
-                Version.V_7_6_0);
+                Version.V_7_5_0);
 
         final Class<? extends ElasticsearchException> exceptionClass;
         final CheckedFunction<StreamInput, ? extends ElasticsearchException, IOException> constructor;