[Request] Replace WebClient with QuarkusRestClient

[andrewazores]

Describe the feature

The Mutiny/Vertx WebClient should be replaced by QuarkusRestClient where possible:

https://quarkus.io/guides/rest-client

This provides more configuration options and nice things like service interfaces rather than dealing with direct HTTP responses.

1. RecordingHelper uses the WebClient for jfr-datasource. This should be pretty easy to convert to a QuarkusRestClient similar to the ReportSidecarService.
2. AgentClient uses the same WebClient for all Agent instance communications. With the new @Url annotation in Quarkus 3.16+ it should also be pretty easy to convert this.
3. ContainerDiscovery uses the WebClient to talk to the Docker or Podman APIs. This may not make sense to port to QuarkusRestClient since this requires a Unix domain socket and Netty native transport.
4. Health uses the WebClient to test other services' health (datasource, dashboard, reports). This looks like it can also be converted easily, and cleanly with @Url.

Anything other information?

See:

• feat(agent): add CRD option to disable hostname verification cryostat-operator#1011
• feat(agent): add option to disable hostname verification #776

Once this is done, hostname verification (and other TLS configuration properties) can be controlled for each particular client, so checks can be disabled only where specifically needed.