Doc: remove dead Banzai Cloud link (#6901)

Looks like Banzai Cloud has migrated their site, and this article has
been lost.

Signed-off-by: Jacob Baungard Hansen <jacobbaungard@redhat.com>

docs/getting-started.md

@@ -148,7 +148,6 @@ See up to date [jsonnet mixins](https://github.com/thanos-io/thanos/tree/main/mi
 * 2018:
   * [Introduction blog post](https://improbable.io/blog/thanos-prometheus-at-scale)
   * [Monzo user story](https://monzo.com/blog/2018/07/27/how-we-monitor-monzo)
-  * [Banzai Cloud hand's on](https://banzaicloud.com/blog/hands-on-thanos/)
   * [uSwitch user story](https://medium.com/uswitch-labs/making-prometheus-more-awesome-with-thanos-fbec8c6c28ad)
   * [Thanos usage](https://www.infracloud.io/blogs/thanos-ha-scalable-prometheus/)