Remove packages 'eclipse' and 'tycho' from CentOS Stream (mark as dead, untag in koji, block in the koji tag, remove from playbooks)

Please carry out the following tasks to remove the package in $subject:

Task 1: Mark package as dead in CentOS Stream (alter its c9s branch in the dist-git repo)
Task 2: Untag package from CentOS Stream koji tags
Task 3: Add package to the blocklist in CentOS Stream koji
Task 4: Remove package from CentOS Stream playbooks
Task 5: [Extra] Also protect pushes to the c9s branch.

Justification 1: This is akin to Fedora's "dead.package" type of activity. The c9s branch in the dist-git repo in Stream needs to be marked in a way that indicates it is no longer part of the OS. This will help with describing how building the OS happens in the community.
Justification 2: The builds also need to be removed from CentOS Stream tags to be excluded from Stream composes. Since Stream doesn't use Errata Tool, we'll be removing packages from both candidate and pending tags here.
Justification 3: While Stream has no concept of versioned releases and there are no package lists to inherit, we might still want to block these packages to ensure they cannot randomly land in our set if someone manages to build them or wants to retag them back in.
Justification 4: This task should also accomplish removal of the package from the CentOS Stream Ansible playbooks. And thus clean our distribution configuration files.