[BIP-782] Enable sUSDX/USDX/aUSDT gauge [Arbitrum]

PR with Payload

https://github.com/BalancerMaxis/multisig-ops/pull/1762

Summary: This is a proposal to enable Balancer gauge on Arbitrum for sUSDX/USDX/aUSDT pool.

References/Useful links:

Link to:

• Website: https://usdx.money/
• Documentation: https://docs.usdx.money/
• Github Page: USDX Token · GitHub
• Communities: X, Telegram, Discord

Protocol Description:

• Stables Labs is a stablecoin infrastructure project, with USDX as its first product.
• USDX is a synthetic stablecoin, designed to offer a stable, censorship-resistant, crypto-native money. USDX captures yield from crypto-native sources and distributes it back to its users.
• sUSDX is a staked version of USDX; yield for sUSDX currently stands around 10%.
• USDT is a fiat-backed USD-denominated stablecoin, issued by Tether.

Motivation:

• Stables Labs has recently concluded Season 1 of its points campaign, and saw rapid increase in its TVL. Our previous collaboration with Balancer has proven extremely effective, as our sUSDX/USDX became Balancer v2 Arbitrum's biggest pool (TVL ~$10M). sUSDX/USDX/aUSDT Balancer v3 pool will allow users to enjoy greater yield, and deep pool of liquidity to swap through.

Specifications:

1. Governance: currently owned by 0x3f9a06aD4c83c289DF83461fE5F24EE4c4491935 (3 out of 4 multisig).
2. Oracles: The protocol does not reply on external oracles.
3. Audits: link. Additional audit reports can be viewed on Audit | usdx.money
4. Centralization vectors: The centralization vectors primarily relate to the owner of the contracts, which is a 3 out of 4 multisig. The team has 15 full-time, doxxed contributors.
5. Market history: USDX has not previously de-pegged, and sUSDX is an ERC4626 token. Balancer pools for USDX/USDT and sUSDX/USDX have just been deployed.
6. Value: USDX currently has $620M in TVL, making it the 4th largest protocol by TVL on BNB Chain, and 5th largest protocol by TVL on Arbitrum. We will also be launching Season 2 of our points program soon, which would bring healthy amount of attention and activities around USDX.

sUSDX -USDX-aUSDT Pool https://balancer.fi/pools/arbitrum/v3/0xc2B0D1A1B4cdDA10185859B5a5c543024c2df869

Child Gauge https://arbiscan.io/address/0x9419c8b7ff370db3823164acea6d9664f4b9c8a9

Root Gauge https://etherscan.io/address/0xeb312b0d7795743C3DE905bc09c0D62aA180A7a6

Technical Specifications:

Transaction: The Balancer Maxi LM Multisig eth:0xc38c5f97B34E175FFd35407fc91a937300E33860 will interact with the GaugeAdderv4 at 0x5DbAd78818D4c8958EfF2d5b95b28385A22113Cd and call the addGauge function with the following arguments:

gauge(address): 0xeb312b0d7795743C3DE905bc09c0D62aA180A7a6

gaugeType(string): Arbitrum

Edits by Maxis:

1. modified child chain and root gauges
2. PR with Payload