Fixes #35399
IIUC, the good-first-issue label and template were meant to make it easier for completely new contributors to get started with something simple. However, I don't think the label and issue template are applicable anymore:
- There are currently no issues with this label, and directing people toward an empty list seems pointless.
- Historically the issue and label has been used rarely. 2026: once, 2025 twice, 2024 thrice. Source: https://github.com/bitcoin/bitcoin/issues?q=state%3Aclosed%20is%3Aissue%20label%3A%22good%20first%20issue%22
- The template has been mis-used, according to #35399
Fix all issues by removing it, since it is clear that it is no longer actively used, nor applicable and possibly a net-negative overall.
Of course, regular devs are still free to open issues of this kind as a normal issue, if they wish. However, having the template for this in this repo and tracking it via a label doesn't seem useful.
Since removing the template and label requires rewriting the "Getting Started" section in CONTRIBUTING.md, I went ahead and also removed the mention of Up for grabs as good things for newcomers to work on. I don't recall the last new contributor that picked something up successfully. Also, Up for grabs is usually stuff that people lost interest in, or is no longer relevant.
Instead I've added a sentence to encourage new contributors to help with critical and broad review, which will naturally guide them to good first follow-up issues to work on.
Meta: I know this topic can be subjective and offer bike-shed potential, but I am happy to iterate a bit on this for a few days.