Set the che.infra.kubernetes.namespace.default property on update of che server

[metlos]

Subtask of #14908

Is your enhancement related to a problem? Please describe.

Che 7.4.0 adds the ability to configure the namespace of a workspace using the new che.infra.kubernetes.namespace.default property. Che operator does not set that property.

Describe the solution you'd like

The operator should set this property to the same value as the legacy che.infra.kubernetes.namespace or che.infra.openshift.project. This will ensure smooth transition into the new way of configuring the workspace namespace.

Describe alternatives you've considered

Additional context

eclipse-che/che-operator#92 sets the new property on new installs. This issue is strictly about the update of an existing che installation using the operator.

[metlos]

I have verified that eclipse-che/che-operator#92 supports also the updates. When a new version of the operator is installed, it upgrades an existing che installation and updates the configmap with the correct value of the new environment variable.