[Whitelisted Caller] Upgrade Kusama RC and system chains to 1.7.1

This is a referendum that obsoletes the existing #582 . This is due to the urgency to add this relay chain fix for the bug that has caused the Kusama stall on top of the 1.7.0 release.

Once enacted, the Kusama Relay Chain and System Chains will be upgraded to the Runtimes 1.7.1 release..

The highlights of the 1.7.0 release are:

Integrating "Empowered XCM Origins" features to System Chains,
Adding Snowbridge V2 pallets, to enable Snowbridge V2 bridging,
Upgrading to the latest Polkadot-SDK (2507) that comes with many fixes and enhancements.

For the full list of changes, please read the fellowship 1.7.0 release notes and 1.7.1 release notes

If approved, it is scheduled to enact at block 29968624, estimated time 2025-09-05 09:59:08 (UTC).

Whitelist: https://kusama.subsquare.io/fellowship/referenda/111

🚨 Important note for Ecosystem builders: 🚨

In preparation for the upcoming Asset Hub Migration we changed the behavior of transfer_assets and (limited_)reserve_transfer_assets extrinsics to remove DOT/KSM support. You can find more information about what is changing, which SDK versions are affected, along with instructions on how to follow up in this guide.

We recommend that Parachains and dapp builders switch to using alternative extrinsics as instructed in the guide above, otherwise cross-chain transfers may start failing.

Edited

Kusama is having a referendum to fix a bug that caused the network to stall.
It replaces an older referendum because the fix is urgent.
The upgrade will bring Kusama to version 1.7.1.
It includes new features like Empowered XCM Origins and Snowbridge V2.
It also upgrades to the latest Polkadot-SDK with many improvements.
If approved, the upgrade will happen at a specific block and time.
Builders need to update their systems to avoid cross-chain transfer issues.

Source