docs: incorrectly recommends `job-json-overrides` for Connect Kubernetes job customization

The Helm documentation at https://docs.posit.co/helm/docs/customize.html#customize-kubernetes-jobs recommends using job-json-overrides to customize Kubernetes jobs for both Workbench and Connect. However, this mechanism does not work for Connect when templates are enabled.

When Launcher.KubernetesUseTemplates = true (now the default), any values set by using job-json-overrides functionality will be ignored.

Since templates are enabled by default for Connect's Kubernetes deployments, Connect users following these docs are directed to a mechanism that is silently ignored.

We've seen this cause some confusion in recent support tickets (https://rstudioide.zendesk.com/agent/tickets/125510, https://rstudioide.zendesk.com/agent/tickets/125515) where customers attempt to configure nodeSelector constraints for Connect using the documented job-json-overrides approach, which silently fails.

Instead this is possible in Connect via settings like launcher.templateValues.pod.nodeSelector and launcher.templateValues.pod.affinity

Start with the Helm documentation at customize.html#customize-kubernetes-jobs, especially the guidance for Workbench and Connect. Update the Connect guidance to explain that job-json-overrides is ignored when templates are enabled and document the launcher.templateValues.pod.nodeSelector and launcher.templateValues.pod.affinity settings; done means the page no longer directs Connect users to the ineffective mechanism.