test/extended/cli/adm_upgrade/recommend: TestRiskA PromQL use max_over_time

Avoid failing on rare flakes like [1]:

  : [Serial][sig-cli] oc adm upgrade recommend When the update service has conditional recommendations runs successfully with conditional recommendations to the --version target [Suite:openshift/conformance/serial]	22s
  ...
  Could not evaluate exposure to update risk TestRiskA (invalid PromQL result length must be one, but is 0)

where there was presumably some kind of hiccup in scraping the
cluster-version operator.  Instead of expecting to find
cluster_version at the single point in time "now", accept it if we
find that metric anywhere in the past hour.

[1]: https://prow.ci.openshift.org/view/gs/test-platform-results/logs/periodic-ci-openshift-release-master-ci-4.20-e2e-aws-ovn-techpreview-serial/1959321955551154176

Author: wking

test/extended/cli/adm_upgrade/recommend.go

@@ -141,7 +141,7 @@ No updates available. You may still upgrade to a specific release image.*`)
           "url": "https://example.com/testRiskA",
           "name": "TestRiskA",
           "message": "This is a test risk.",
-          "matchingRules": [{"type": "PromQL", "promql": {"promql": "group(cluster_version)"}}]
+          "matchingRules": [{"type": "PromQL", "promql": {"promql": "group(max_over_time(cluster_version[1h]))"}}]
         }
       ]
     }