rewrite retest robot comment

1. The Kubernetes project should not have merge-blocking tests that are too flaky to consistently pass, we've worked hard to eliminate these, and if they come up again it should not be treated as normal

2. The text here is way too long, we should focus on the most essentail details. The contributor does not need to know the search query and we're not even including all of it.

3. Prioritize encouraging helping fix test flakes early in the message instead of ~at the end.

4. The full test history link is already included in test failure comments.

Author: BenTheElder

config/jobs/kubernetes/sig-k8s-infra/trusted/sig-contribex-k8s-triage-robot.yaml

@@ -290,19 +290,9 @@ periodics:
       - --token=/etc/github-token/token
       - --endpoint=http://ghproxy.test-pods.svc.cluster.local
       - |-
-        --comment=The Kubernetes project has merge-blocking tests that are currently too flaky to consistently pass.
+        --comment=Retesting failed PR that otherwise appears ready for merge.
 
-        This bot retests PRs for certain kubernetes repos according to the following rules:
-        - The PR does have any `do-not-merge/*` labels
-        - The PR does not have the `needs-ok-to-test` label
-        - The PR is mergeable (does not have a `needs-rebase` label)
-        - The PR is approved (has `cncf-cla: yes`, `lgtm`, `approved` labels)
-        - The PR is failing tests required for merge
-
-        You can:
-        - Review the [full test history](https://prow.k8s.io/pr-history/?org={{.Org}}&repo={{.Repo}}&pr={{.Number}}) for this PR
-        - Prevent this bot from retesting with `/lgtm cancel` or `/hold`
-        - Help make our tests less flaky by following our [Flaky Tests Guide][1]
+        Please help us fix flaky tests by following our [Flaky Tests Guide][1]
 
         /retest-required