Connection Timeout when running tasks in Che-Theia behind a proxy

When running CRW 2.2.0 behind a proxy, with proxy settings set in the `CheCluster` custom resource, it is not possible to run tasks inside the Che-Theia IDE.

The task output doesn't respond for a while (1 or 2 minutes), and finally triggers this error:

Failed to execute Che command: connect ETIMEOUT 3.136.29.207:443

We confirmed that the involved IP is the router load-balancer IP of the OpenShift cluster on which the workspace is running.

The behavior seems typical from a situation where Che-Theia tries to reach a workspace endpoint without using the Proxy settings configured in the Che cluster.

ADDITIONAL NOTE: This error was spotted in CRW installed on a disconnected cluster, following the typical restricted network installation process. But it is obviously more generally proxy-related, related to the fact that a proxy is usually used in this type of installation.