Add expiry trigger for expired AmuletTransferInstructions

[meiersi-da]

Keeps the ACS size low, and improves the UX, as users don't have to take an action to clean them up.

Relevant code:

• splice/daml/splice-amulet/daml/Splice/AmuletTransferInstruction.daml

  Lines 15 to 21 in be95606

  	-- | A transfer instruction for transferring Amulet tokens pending on receiver
  	-- acceptance.
  	template AmuletTransferInstruction
  	with
  	lockedAmulet : ContractId LockedAmulet -- ^ Locked amulet that holds the funds for executing the transfer upon acceptance
  	transfer : Splice.Api.Token.TransferInstructionV1.Transfer
  	where

• splice/token-standard/splice-api-token-transfer-instruction-v1/daml/Splice/Api/Token/TransferInstructionV1.daml

  Lines 12 to 43 in be95606

  	-- | A specification of a transfer of holdings between two parties.
  	data Transfer = Transfer with
  	sender : Party
  	-- ^ The sender of the transfer.
  	receiver : Party
  	-- ^ The receiver of the transfer.
  	amount : Decimal
  	-- ^ The amount to transfer.
  	instrumentId : InstrumentId
  	-- ^ The instrument identifier.
  	requestedAt : Time
  	-- ^ Wallet provided timestamp when the transfer was requested.
  	-- MUST be in the past when instructing the transfer.
  	executeBefore : Time
  	-- ^ Until when (exclusive) the transfer may be executed. MUST be in the
  	-- future when instructing the transfer.
  	--
  	-- Registries SHOULD NOT execute the transfer instruction after this time,
  	-- so that senders can retry creating a new transfer instruction after this time.
  	inputHoldingCids : [ContractId Holding]
  	-- ^ The holding contracts that should be used to fund the transfer.
  	--
  	-- MAY be empty if the registry supports automatic selection of holdings for transfers
  	-- or does not represent holdings on-ledger.
  	--
  	-- If specified, then the transfer MUST archive all of these holdings, so
  	-- that the execution of the transfer conflicts with any other transfers
  	-- using these holdings. Thereby allowing that the sender can use
  	-- deliberate contention on holdings to prevent duplicate transfers.
  	meta : Metadata
  	-- ^ Metadata.
  	deriving (Show, Eq)

Determine expiry based on transfer.executeBefore.

Make sure to include it in release notes to avoid surprises for users.

@ray-roestenburg-da @OriolMunoz-da : this slipped our attention when implementing transfer support. If you could slip that in sometime (e.g., as a tech-debt item), then that would be great.

[ray-roestenburg-da]

Thanks, we'll try to slip it in somewhere