server-ci.yml always triggers now, but ci-report and ci-artifacts were
missed when #37557 gated the other jobs on needs.go.outputs.relevant-changed.
On PRs that don't touch server code, build-mattermost-server and the test
jobs are skipped, so ci-artifacts fails trying to download a
server-dist-artifact that was never uploaded, and ci-report fails trying
to validate test logs that don't exist. Skip both cleanly instead.
Co-authored-by: Cursor <cursoragent@cursor.com>