Set EE banner to true or false in blog posts

From chat conversation

annabel [19:56]: Have we always had the GitLab Enterprise Edition free trial fixed banner at the bottom of each blog post?

annabel [20:01]: Nevermind, looks like @seanpackham added it in November. Any plans to get rid of it? I might be the only one, but I find it really distracting/annoying when trying to read the actual blog content

amanda [20:03]: I think it's being used to see some metrics on content generating leads...maybe we can just make it less jarring

marcia [20:19]: @Annabel this was first implemented as an option (ee_cta: true set to true of false in the post frontmatter), to be available for certain posts, like the Master Plan one and other promotional content. But at some point someone set it to be included by default in all posts, and it’s not a true/false option anymore. I’d reconsider that as well (at least make ee_cta: false an option). Thoughts?

annabel [20:21]: @marcia oh that’s a way better idea! I think it should depend on the content of the post. For example if a user is reading about the db incident, or about using Vue.js, they’re probably just there to read the content and the banner just gets in the way. But if its a release post that talks about EE features, it makes more sense to have it

marcia [20:22]: Agreed! That was the original purpose of the banner

Todo

Make the EE banner optional for blog posts. The default value can be set to true, but it's important to have an option to not have it. The one in the DB post was reason for a lot of trolls on HN and Reddit.

cc/ @annabeldunstone @erica @regisF @seanpackham Anyone against it? If not, I'll ask if @iamphill can make this for us.