[stable2503] Backport #7607

[paritytech-cmd-bot-polkadot-sdk]

Backport #7607 into stable2503 from re-gius.

See the documentation on how to use this bot.

[paritytech-cmd-bot-polkadot-sdk]

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin backport-7607-to-stable2503
git worktree add --checkout .worktree/backport-7607-to-stable2503 backport-7607-to-stable2503
cd .worktree/backport-7607-to-stable2503
git reset --hard HEAD^
git cherry-pick -x 3dc3a11cd68762c2e5feb0beba0b61f448c4fc92
git push --force-with-lease

[github-actions]

This pull request is amending an existing release. Please proceed with extreme caution,
as to not impact downstream teams that rely on the stability of it. Some things to consider:

• Backports are only for 'patch' or 'minor' changes. No 'major' or other breaking change.
• Should be a legit fix for some bug, not adding tons of new features.
• Must either be already audited or not need an audit.

Emergency Bypass

If you really need to bypass this check: add validate: false to each crate
in the Prdoc where a breaking change is introduced. This will release a new major
version of that crate and all its reverse dependencies and basically break the release.

[re-gius]

This PR will be the "final" step for v16 metadata. Exposing this in 2503 will help gather feedback on v16 from the community to make it stable in the next stable release.

[jsdw]

LGTM, though I am not super familiar with the backport rules here; the doc says to only backport fixes and not features, but not sure how strictly we adhere to this!

Getting this into a release would allow testing the "candidate" V16 metadata on live nodes sooner I guess, but people can build and test against the kitchensink runtime or polkadot master etc if backporting this isn't desirable.