release steps: make Product team self-sufficient

Created by: sourcegraph-bot

The Distribution release tracking issue currently requires we notify the Product team on three different occasions:

...

• Verify by posting in #product that there is a draft of the release blog post. ...
• Post in #product and verify the blog post is ready to be merged. ...
• Ask the product team to merge the blog post (example).

Our releases occur on a single/static fixed date, the 20th, we should not be the ones to follow up on product/marketing posts and should find a way to make the Product team self sufficient in the release process.

Effectively, I believe this just requires we confirm with them that we stop notifying them about this is OK (and they do it themselves internally the same as they would otherwise), and removing these steps from our release tracking issue template.