[Cloud Run Jobs] Specify minimum serverless-init version (#33217)

* fix "serverless-init" text

* specify minimum serverless-init version

Author: nhulston

layouts/shortcodes/serverless-init-install.html

@@ -1,5 +1,6 @@
-{{ if eq (.Get "cloudservice") "jobs" }}<div class="alert alert-info">Serverless-init automatically creates a span for the duration of a task, even if the tracer is not installed. You can disable this by setting <code>DD_APM_ENABLED=false</code>. However, tracing is <strong>recommended</strong> because it is required for task-level visibility.</div>{{ end }}
-Datadog publishes new releases of the `serverless-init` container image to Google's gcr.io, AWS's ECR, and on Docker Hub:
+{{ if eq (.Get "cloudservice") "jobs" }}<div class="alert alert-info">Serverless-init automatically creates a span for the duration of a task, even if the tracer is not installed. You can disable this by setting <code>DD_APM_ENABLED=false</code>. However, tracing is <strong>recommended</strong> because it is required for task-level visibility.</div>
+<div class="alert alert-info">Cloud Run Jobs requires <code>serverless-init</code> version 1.9.0 or later.</div>{{ end }}
+Datadog publishes new releases of the <code>serverless-init</code> container image to Google's gcr.io, AWS's ECR, and on Docker Hub:
 
 | hub.docker.com | gcr.io | public.ecr.aws |
 | ---- | ---- | ---- |