[Monitoring] Remove sync Call

[pickypg]

elasticsearch/x-pack/plugin/monitoring/src/main/java/org/elasticsearch/xpack/monitoring/exporter/http/VersionHttpResource.java

Line 59 in e91f404

return validateVersion(client.performRequest(request));

We should convert this to be an async call like the rest of the Monitoring resource code. As it is, the synchronous call has a 30s timeout can be more flexible by making it async.

[elasticmachine]

Pinging @elastic/es-core-features