Remove old illustrations

Purpose

geo-empty -> gitlab!142163 (merged)

geo-replication-empty -> gitlab!144665 (merged)

cluster_popover -> gitlab!145185 (merged)

pipelines_failed -> gitlab!145650 (merged)

empty-state-agents -> gitlab!146358 (merged)

empty-terraform-register-lg -> gitlab!146487 (merged)

profile_private_mode -> gitlab!146490 (merged)

no_commits -> gitlab!146531 (merged)

alert-management-empty-state -> gitlab!146534 (merged)

incident-empty-state -> gitlab!146537 (merged)

service_desk_callout -> gitlab!146549 (merged)

Checklist

For a new icon and/or illustration:

• Link to related design issue:
• If this adds an icon ensure that it follows the new icon checklists.
• If this adds an illustration ensure that it follows the new illustration checklists.

For third-party trademarks:

• If this adds or updates an icon or illustration that includes a third-party trademark, ensure that it follows the process for adding third-party trademarks to GitLab.

gitlab#424397 (closed)