Theia cannot reach the API server with both TLS and proxy enabled

When both TLS and http proxy are enabled, it seems that Theia cannot reach the Che server API endpoint by its external URL.

This becomes critical now that TLS is enabled by default to have webviews working.

This might be related to this Axios bug: axios/axios#925 (comment)

Corresponding upstream issue: https://github.com/eclipse/che/issues/16356