[Release process] Improve the release announcement crafting process

[deepakpathania]

Problem statement

The release lead has to spend a lot of time to craft the release announcement (What's new) post while trying to gather screenshots/details from multiple PRs and issues. The docs tell leads to populate a draft throughout the release process so that at the end it's easier but it isn't always followed. And at the end, since this isn't something we explicitly have any training for leads, the quality of the announcement posts can vary from one release to another.

Acceptance criteria

Improve the current crafting process to minimise the time it takes for release leads to publish it, while introducing some standardisation.

Ideas

• Scraping GH PRs that were included in the release to create a draft post.
• Offloading the release notes process to product teams to change the notes to be more feature-oriented.
• Automate generation of the release post in some other way? (TBD)