chore: Fix local testnet scripts and cleanup

[Reecepbcups]

What is the purpose of the change

• Fixes multinode-local-testnet.sh script
• Cleans up redundant lines in multinode-local-testnet.sh & superfluid-test-startnode.sh

Brief Changelog

• Fixes issue with validator2 being set with validator3 setting in config.toml
• Improve readability
• Reduces time to start by 21 seconds
• Adds error check
• Kills osmosisd locally when you run multinode-local-testnet

Testing and Verifying

• Manually verified via running both scripts locally & checking tmux instances are working as intended.
• queried each RPCs status

Documentation and Release Note

• Does this pull request introduce a new feature or user-facing behavior changes? no
• Is a relevant changelog entry added to the Unreleased section in CHANGELOG.md? no
• How is the feature or change documented? not applicable