fix route reports for custom backends

[stevenctl]

This message is wrong; plugin backend types should't write this status.

    - lastTransitionTime: "2024-11-15T19:38:52Z"
      message: invalid backend type provided
      observedGeneration: 6
      reason: InvalidKind
      status: "False"
      type: ResolvedRefs

[danehans]

A few nits. Otherwise LGTM.

[danehans]

The Kubernetes Tests / End-to-End (cluster-six) job is failing due to:

Gloo was successfully uninstalled.
--- FAIL: TestK8sGateway (229.49s)
    --- PASS: TestK8sGateway/HTTPRouteServices (89.12s)
        --- PASS: TestK8sGateway/HTTPRouteServices/TestConfigureHTTPRouteBackingDestinationsWithService (46.65s)
        --- PASS: TestK8sGateway/HTTPRouteServices/TestConfigureHTTPRouteBackingDestinationsWithServiceAndWithoutTCPRoute (42.47s)
    --- FAIL: TestK8sGateway/TCPRouteServices (65.56s)
        --- FAIL: TestK8sGateway/TCPRouteServices/TestConfigureTCPRouteBackingDestinationsWithMultiServices (65.56s)

#10398 may help with this flake. I am rerunning the failed job.

[danehans]

@stevenctl make generate-changelog and mv changelog/v1.18.0-rc2/custom-be-route-report.yaml to the newly generated changelog to fix the failing changelog-bot job. cc: @sam-heilbron