Drop FAILED status from access review campaigns

Source fetch failures stay surfaced on the source fetch (status and
last error) instead of failing the entire campaign, so reviewers can
proceed on the sources that succeeded.

Signed-off-by: Bryan Frimin <bryan@getprobo.com>

pkg/server/api/mcp/v1/specification.yaml

@@ -7189,7 +7189,6 @@ components:
         - DRAFT
         - IN_PROGRESS
         - PENDING_ACTIONS
-        - FAILED
         - COMPLETED
         - CANCELLED
       go.probo.inc/mcpgen/type: go.probo.inc/probo/pkg/coredata.AccessReviewCampaignStatus