This issue is about to run the release process for 3.10 normally (but WITHOUT producing any release).
That will generate all the stuff everywhere (git repos, tracker versions, filters, fields...), leading to a manageable MOODLE_310_STABLE branch.
- Run the process (creating branches, tracker fields, CI jobs, security...)
- Rename current version 4.0 to 3.10 (Nov 2020)
- Create new version 4.0 (Nov 2021)
- Modify all the issues in the Tracker commenting about 4.0 to 3.10 (and 4.1 to 3.11, 4.2 to 4.0, 4.3 to 4.1...).
- Verify that 4.0 is upgradeable from 3.10 (adjust the "compare databases" job in master to cover that).