Set the memory allocation of the ckUSDT archive canister

Proposal to change the memory allocation of the ckUSDT archive canister

Target canister: yhujl-liaaa-aaaar-qaiha-cai

New memory allocation: 2_147_483_648

Previous ckUSDT archive proposal: https://dashboard.internetcomputer.org/proposal/143942

Motivation

Set the memory_allocation of the ckUSDT archive canister from its current value of 0 (best-effort) to 2_147_483_648 (2 GiB). The current value can be obtained by calling the canister_status endpoint of the NNS root canister.

With a best-effort allocation, every memory growth on a subnet above its storage reservation threshold has to reserve cycles up front, and is rejected once the canister's reserved_cycles_limit is exhausted. With a reserved allocation the amount charged is the change in max(allocation, usage), which stays constant while usage is below the allocation, so growth within the allocation reserves nothing and cannot be rejected on those grounds.

Block archiving is currently disabled on this ledger, so the archive is not growing and this allocation is precautionary: it is in place for when archiving is switched back on. 2 GiB matches the allocation the ckBTC archive already has. Note that a full archive node holds more than this - node_max_memory_size_bytes is 3 GiB of block data alone - so archive allocations will need revisiting as part of re-enabling archiving.

The canister currently uses 196 MiB, so this leaves 1.81 GiB of headroom. Setting an allocation is itself charged a reservation proportional to the subnet's storage saturation at the time; the fiduciary subnet is currently far below its 750 GiB reservation threshold, so this proposal reserves no cycles. A reserved allocation is charged whether or not it is used, at roughly 26.2T cycles per GiB per year on this 34-node subnet - about 52.4T cycles per year for the full 2 GiB. The canister is already billed for the memory it uses, since storage is charged on max(allocation, usage), so the incremental cost is that of the currently-unused headroom.