Switch script links to KCS URLs

Problem: links to scripts from docs don't work. Apparently, they're blocked by the Customer Portal for security reasons. Yesterday, Fabrice submitted a fix that used links to GH in upstream, but Support doesn't like it. So, we need to link to *.redhat.com somewhere. For that, I created a Knowledgebase 'solution' with the scripts as attachments: https://access.redhat.com/solutions/6963399

Now we need to update our docs to use the links to these attachments. This will require different links in upstream (linking to GH) and downstream (linking to the Knowledgebase attachments). So, we'll need to create attributes for the URLs and define them differently for upstream and downstream. In the docs, the links to the scripts are at:

Upstream:

• https://www.eclipse.org/che/docs/stable/administration-guide/installing-che-in-a-restricted-environment/
• https://www.eclipse.org/che/docs/stable/administration-guide/upgrading-che-7-41-on-openshift/

Downstream:

• https://access.redhat.com/documentation/en-us/red_hat_openshift_dev_spaces/3.0/html/administration_guide/installing-devspaces#installing-devspaces-in-a-restricted-environment-on-openshift
• https://access.redhat.com/documentation/en-us/red_hat_openshift_dev_spaces/3.0/html/administration_guide/upgrading-devspaces#upgrading-crw-2.15-on-openshift

The files in which the links are:

• https://github.com/eclipse-che/che-docs/blob/main/modules/administration-guide/partials/snip_preparing-images-for-a-restricted-environment.adoc
• https://github.com/eclipse-che/che-docs/blob/main/modules/administration-guide/pages/upgrading-che-7-41-on-openshift.adoc

And in downstream:

• https://gitlab.cee.redhat.com/red-hat-developers-documentation/red-hat-devtools/-/blob/master/docs/topics/devspaces/administration-guide/snip_preparing-images-for-a-restricted-environment.adoc
• https://gitlab.cee.redhat.com/red-hat-developers-documentation/red-hat-devtools/-/blob/master/docs/topics/devspaces/administration-guide/upgrading-che-7-41-on-openshift.adoc