Decommission gating-reporter

We now rely on KQE pipelines testing brew builds and the RHEL on Gitlab uses the draft builds as replacement for Brew scratch builds. With that, gating-reporter shouldn't be needed anymore.

• Send email announcing we intend to drop support for running tests for scratch builds on brew and wait for feedback (1 week should be enough) https://groups.google.com/a/redhat.com/g/cki-announce/c/zGL1NG2ER3k/m/QfIhK7xiAwAJ
• Disable gating-reporter deployment and announce and wait 1 week for feedback
• Delete all references for gating-reporter

Jira: CKI-6529

Jira: CKI-7462