Fix missing BoundedVec::truncate_from

[franciscoaguirre]

This backport should've had these changes.

[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.

[paritytech-workflow-stopper]

All GitHub workflows were cancelled due to failure one of the required jobs.
Failed workflow url: https://github.com/paritytech/polkadot-sdk/actions/runs/14136260019
Failed job name: quick-benchmarks-omni

[acatangiu]

@franciscoaguirre maybe fix it directly here #8089, that’s the PR that tries to get whole CI green again for the 2503 branch

[franciscoaguirre]

@franciscoaguirre maybe fix it directly here #8089, that’s the PR that tries to get whole CI green again for the 2503 branch

Closing in favor of #8089. Already cherry-picked the commit there