feat: upgrade to Polkadot v0.9.25

[wischli]

fixes KILTProtocol/ticket#2087

• Upgrades to latest Polkadot v0.9.25
• Removes Launch Pallet removal migration
• No migrations required since we don't use Parity DB

Noteworthy PRs from Substrate that influenced changes:

• remove_prefix deprecation Safe and sane multi-item storage removal paritytech/substrate#11490
• EnsureOneOf deprecation Several tweaks needed for Governance 2.0 paritytech/substrate#11124
• Move ExportGenesisStateCommand and ExportGenesisWasmCommand to cumulus-client-cli paritytech/cumulus#1325

Checklist:

• I have verified that the code works
  • No panics! (checked arithmetic ops, no indexing array[3] use get(3), ...)
• I have verified that the code is easy to understand
  • If not, I have left a well-balanced amount of inline comments
• I have left the code in a better state
• I have documented the changes (where applicable)

[ntn-x2]

LGTM!

[trusch]

I think paritytech/substrate#11431 is worth mentioning. It enables the storage transaction support for all extrinsics if I understand it right, so we don't have to take care of strictly first checking everything and then writing to storage.