Improve when we display GCP credit banner

We recently received feedback that it is not always appropriate to display the GCP credit banner on the Kubernetes page:

Advertising for Google Cloud on the CI Kubernetes page is just plain tacky. I'm sure there's a way to turn this off, but I shouldn't have to in the paid Enterprise product.

Personally speaking, I agree that it's a huge boon and definitely worth calling out.

Professionally speaking, as a user of the paid product, I wish there was a way to squelch the notification globally. The decision of what cloud provider to use and whether we can crunch company data on them is made well above the heads of any of our developers, so it amounts to noise a best, a reminder of something awesome we can't have at worse.

We already dismiss the banner globally if the user closes it. We should consider how to improve notifying users of free credit without pushing it on them, esp for already paying customers.