private void addOtelcol(TreeConfigProducer<?> parent, DeployState deployState, HostResource hostResource) {
        var otelcol = new OpenTelemetryCollector(parent, deployState);
        otelcol.setHostResource(hostResource);
        otelcol.initService(deployState);
    }
Builds the admin model from a version 4 XML tag, or as a default when an admin 3 tag or no admin tag is used.

@author bratseth
config-model/src/main/java/com/yahoo/vespa/model/builder/xml/dom/DomAdminV4Builder.java