Automate EVM end-to-end load testing with flood (weekly)

[gyuho]

https://www.paradigm.xyz/2023/06/flood

1. Set up a pool of VPCs
2. Weekly trigger scalability testing job on subnet-evm
3. Reuse existing VPC to set up a custom network with subnet-evm (latest binaries)
4. Integrate install-subnet-chain command into avalancheup-aws apply so there's only a single command to install everything
5. Download install "flood"
6. Run against the custom network
7. Report results back

[hexfusion]

cc @marun