gitchangelog workflow feedback

Comments on gitchangelog version from MR !9295 (merged), experience gathered from 9.21.0, 9.20.1, and 9.18.29 releases:

TL;DR it's currently more work to prepare release notes than it used to be. See individual discussion threads below for details.

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information